How Much Water Do You Really need?

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Conventional wisdom will tell you that you need eight glasses a day.

We all know we should drink water and stay properly hydrated, but how much do we REALLY need?  How much is too much?  What about sports drinks like Gatorade – is there a time and place to consume them?

Today on Nerd Fitness we’re going to bust all of the myths associated with water, determine how much water you should consume, and how that changes if you’re exercising regularly.


Do i need 8 glasses of water every day?

drop of water

First and foremost, yes you need water.

Boom. Article done. I’m going on break.

Water is good for you; a significant portion of your body is composed of water, and when you lose fluids through sweat, exertion, bodily functions, etc, consuming water can help you replenish fluids.


The whole “8 glasses of water a day” thing is not law.  In fact, there’s no real proof of this being a proper amount at all.

As we’ve told you before (the perfect workout, the perfect diet), we are all unique snowflakes, and we all require different amounts of water!  Somebody that exercises with regularity and goes on a lot of long runs will require more water than somebody who exercises less regularly. There’s no exact amount of water that works for everybody.

So where did this magical “8 glasses of water a day” number initially come from?  Nobody really knows.  According to Snopes:

Back in 1945 the Food and Nutrition Board of the National Research Council stated that adults should take in about 2.5 liters of water per day (which is roughly the equivalent of eight glasses of water), but it also noted most of that intake level was already satisfied through the consumption of food without the need for the additional drinking of water.

That’s right, you get a SIGNIFICANT amount of water from the food you are consuming.  A huge percentage of our bodies is made of water, a huge percentage of the planet is made up of water…why wouldn’t a huge percentage of our food be composed of water too?

So, yes. Consuming water is important.  But the 8 glasses a day case doesn’t hold water (ha!), as we get a significant portion of our daily water from our food we consume.  Things like fruits and vegetables, even meat, is composed of a tremendous amount of water, all of which counts towards our ‘hydration quotient’ for the day.

You know what else counts? EVERY OTHER BEVERAGE WE DRINK!

Things like tea, coffee, even dreaded sugary beverages, milk, juices, and alcoholic beverages.

How much water DO you need?


So you know you don’t need to always drink 8 glasses, it could be less and it could be more.  So how much do you need?

Honestly?  Drink when you are thirsty. That’s it.  I’m going on a second break!

Kidding.  Seriously though, your thirst is a pretty damn good indicator of when you should consume more water.  Do you think dogs and cats and elephants worry about hydration levels?  Nope – they simply consume water when their body tells them that they are thirsty.

As nerds, we tend to overthink, overanalyze, and drive ourselves crazy with too much info.

Now, if you happen to be one of those people that needs MORE advice than that, check your urine color.

Weird, I know.

This chart provides a great color test.  You want to aim (not literally) for a “pale straw” or “lemonade” color.  I’m not quite sure what color “pale straw” is, but everybody knows what lemonade looks like.  If your pee is starting to resemble lemon-lime gatorade, you’re dehydrated.  If your pee comes out a different color all together, I would probably seek medical attention immediately. You’re welcome :)

And if your pee smells funny, don’t forget that you probably ate asparagus last night!

So what are the tell tale signs that something is wrong, that you are dehyradated?

According to the National Institute of Health, your primary signs of dehydration are:

  • A feeling of thirst (duh)
  • Dry or sticky mouth
  • Low or no urine output; urine looks dark yellow
  • Sunken eyes
  • Lethargy

Yes, SEVERE dehydration can lead to significant issues, even comas.  We’re going to try and avoid those.

Now, if you are feeling one or some of these symptoms, it’s possible you are dehydrated.  Now, there’s yet another myth running around that says “if you are feeling thirsty, it’s already too late and you’re already dehydrated.”

This is also not true.  If you are feeling the signs of dehydration, consuming some water can get you right back on track.

I now hear you saying: “Okay Steve, I got it.  If I feel dehydrated, I’ll drink more water.  To prevent that from happening, why don’t I just drink more water all of the time, even when I’m not thirsty!?”

Great question, my dear friend.   

Can I be over-hydrated?


Believe it or not, this whole “hydration science” thing has been severely blown out of proportion.  

How and why? One dude who decided if some water was good, more water must be better. Then, bandwagoners jumped on board with that idea, without things like “evidence” or “scientific proof” (much like the wrongful vilification of fat).

From Outdoors:

A single individual working for the U.S. military decided that water was a tactical weapon. That if the military could be encouraged to drink more during maneuvers, they’d have less heat stroke and less illness and they’d be more productive and could be better soldiers. It was purely his idea. It had no scientific basis at all. Two years later he published a paper supposedly saying that if the US soldiers drank 1.9 liters per hour [64 ounces] when they were exercising in the heat they would perform much better. There was utterly no concrete evidence that that was true. The problem was, his advice was embraced by the U.S. Military. They changed their drinking guidelines to say that you should now drink 1.9 liters per hour. The same people who drew up those guidelines were then invited by the American College of Sports Medicine to get involved with drawing up guidelines for runners.

In 1996, that culminated with the new American guidelines, which said that you must drink as much as tolerable during exercise, up to 40 ounces per hour. That became the mantra—that you had to drink before you became thirsty, and as much as possible during exercise. It was after that the problems of hyponatremia really become problematic around the world.

Combine this with the sports beverage industry (which I’ll skewer in a minute) and the bottled water industry (one of the best scams going, which I’ll get to as well), and you have a marketing engine that won’t slow down.

“Drink before you’re thirsty or it’s too late.”  ”Running a marathon?  It’s better to overhydrate then not drink enough! Better safe than sorry!”

Actually, you CAN overhydrate, and it can be dangerous – it’s called hyponatremia, it’s an electrolyte imbalance from too much water consumed, and it’s bad news bears.

Want to know the people who suffer from hyponatremia the most?

Marathon and ultra runners.

Dr. Timothy Noakes, author of Waterlogged, explains that the overconsumption of water can lead to our body developing a severe imbalance of sodium in our systems, which can lead to a litany of side effects, even death.

What he’s found of people who have dealt with cases of exercise-induced hyponatremia:

“What I’ve found is that all of these people were probably drinking 1.2 liters per hour [40 ounces]. They continue to drink like that for four or five hours. Now, normally, if you’re drinking at that rate, you simply pass it out as urine. A person who is overdrinking will start passing urine so frequently that they’ll realize, This is stupid. I’m going to stop drinking.

But what happens in hyponatremia is that, for some reason, the brain interprets that the person is dehydrated and secretes the antidiuretic hormone. As a consequence, that prevents all urine production. Although they are sweating, they may be sweating at a rate of 20 ounces per hour, but they are drinking at a rate of 40 ounces per hour. Every hour they are accumulating 20 ounces. You can do that for a couple of hours, but once you’ve accumulated about 60 to 80 ounces of water in your body, all of your tissues become bloated, and the organ that becomes most affected is the brain.

The brain swells, and because it is in a rigid skull, it cannot swell very much. The more it swells, the more pressure, and that eventually squeezes the arteries supplying blood to the brain. Ultimately, there is less oxygen getting to the brain, and certain parts become damaged. “

Not good. One 2002 study found that 13% of Boston Marathon runners experienced hyponatremia. While many experience hyponatremia without being in immediate danger, it certainly isn’t healthy.

So, how do you combat this? Drink when you are thirsty!  LISTEN TO YOUR BODY!

Time to answer your next question: “If drinking too much water causes an issue with sodium imbalances, what about sports drinks? They have electrolytes and sodium in them!”

Allow me!

What about sports drinks like Gatorade?


Michael Jordan is famously seen drinking gatorade during his flu game in 96, which tells us that without gatorade he wouldn’t have been able to play:


Little do they tell you that Michael also had another secret weapon at his disposal that helped him play up to snuff in that game: apple sauce!

So why is that famous commercial all about Gatorade and not about apple sauce? Because there’s wayyyy more money in the sports beverage industry, and they can sell on the term “replenish electrolytes” which is actually way simpler to do than they make it out to be.

We’re promised that without the careful combination of electrolytes and ingredients in Gatorade, we’re going to get dehydrated when exercising and suffer.

Here’s what happens: When you sweat, you lose fluids and electrolytes, especially sodium and chloride (which is why your sweat tastes salty…stop tasting your sweat you creep).  Now, when you’re lacking fluids and electrolytes, your muscles and performance can suffer.

So that’s where Gatorade ALLEGEDLY will solve all of your problems.

Here’s the truth: unless you are exercising for hours and hours and hours, your electrolyte imbalance will not cause a drop in performance.  If you are exercising for an hour or less, some sips of water to quench your thirst is more than enough.  If you are exercising for hours upon hours, then additional products may help.

In these instance, Gatorade could help potentially, but there’s nothing in Gatorade that’s magic. It’s sugar, water, sodium, potassium, and then some artificial and natural flavoring to make it taste and look the way it does.

Want the benefits of gatorade while on your marathon run without having to buy gatorade? Make your own!

As Al Kavado talks about here, try mixing water, honey, salt, and/or lemon juice.  Try different combos (mixing in some OJ or using coconut water!)

And just like that you, you have your sodium, some sugars, and rehydration.  No fancy marketing required.


Do some boring cardio for 20 minutes (which burns a minimal number of calories), and then chug a 32 oz gatorade (200 calories and 50+ grams of sugar!) and think you’re healthier. Negatory!

Water works just fine for 98% of the activities you will ever do.

what about coffee?

coffee cup

Time to put the myth busting cap back on: You’ve probably been told that drinking caffeinated beverages will dehydrate you.

That by consuming caffeinated beverages, you’re actually expelling more water than you are consuming.

This is another one of those bits of conventional wisdom hat gets blown way out of proportion.

Yes, caffeine is a mild diuretic.  However, our bodies are pretty darn smart, and because all drinks are composed almost entirely of water, it more than makes up for the effects.

As pointed out here in this study:

Ingestion of caffeine in large doses (at least 250-300 mg, equivalent to the amount found in 2-3 cups of coffee or 5-8 cups of tea) results in a short-term stimulation of urine output in individuals who have been deprived of caffeine for a period of days or weeks. A profound tolerance to the diuretic and other effects of caffeine develops, however, and the actions are much diminished in individuals who regularly consume tea or coffee. Doses of caffeine equivalent to the amount normally found in standard servings of tea, coffee and carbonated soft drinks appear to have no diuretic action.

What about alcohol?  Same thing. Alcohol has diuretic properties, but only causes dehydration when consumed at beyond normal levels.  (Here’s our thoughts on being a healthy nerd that still can still enjoy an occasional cocktail.)

What ALLLLL OF THIS MEANS: Drink when you are thirsty. All liquids you consume count towards hydration, and only in cases of overconsumption can they negatively affect your hydration.

Beware the bottled water hype

bottled water

In 2012, total U.S. bottled water consumption increased to 9.67 billion gallons, up from 9.1 billion gallons in 2011.  Every person in America drank an average of 30.8 gallons of bottled water last year.  Bottled water sales increased by 6.7 percent in 2012, and now total $11.8 billion.

Only in America can an industry selling tap water in a plastic bottle become an absolutely juggernaut, as Lewis Black so eloquently points out (NSFW Language):


It is very likely that your local tap water is fine! Check your local government for more information, but if you live in the United States, chances are your tap water is equal or better to the bottled stuff! Heck Coca-Cola knows this, as their Dasani Brand is ultimately filtered tap water.

Want that bottle of Fiji water because it’s clean and pure and provides you with magical abilities like Percy Jackson? There is less arsenic in Cleveland Tap water than Fiji water!  Much less expensive too :)

If you don’t like the taste of, or are concerned about your local tap water, try a Brita filter or something equivalent. Stop going through hundreds of plastic bottles of water every year, and drink the water you already have available to you.

Yes, if the choice is between no beverage, a coke, or a bottle of water, go with the bottled water!

Just don’t go out of your way to buy water from the polar ice caps, Hoth glaciers, or the Swiss Alps because you think it’s going to be healthier for you, provide you with more of a benefit than regular water.  That’s all hype, sucka!

Read more about bottled water hype here at WiseBread.

If you are going to bring water with you, follow these guidelines as to what kind of container you’ll use.

After doing our own research, we ultimately decided on stainless steel for Nerd Fitness water bottles for the reasons above.

okay so what do i do?

glass of water

“Ugh, Steve, you just spent 2300 words ripping apart water.  I thought water was important!”

Yes, yes it is.

Water keeps your body functioning properly.  Consume it when you feel the need and your thirst will be quenched, your body will stay regulated, and you will live to see tomorrow.

On top of that, consuming water before a meal can help you feel fuller and thus prevent you from overeating.  If this works for you, keep doing what you’re doing!

Water should definitely be consumed when you are thirsty!  But the importance of water has been overblown, and you don’t need to spend hundreds of dollars each year on fancy bottled water from glaciers.

Here’s everything in a nutshell:

  • Chill out about water, don’t overthink it.
  • Drink when you feel thirsty.
  • If your pee is a darker color than normal, drink more water. If it’s lighter than normal, drink less.
  • Don’t stress about drinking water neurotically throughout the day.
  • Dont bother with the energy drinks unless your exercise is intense, over several hours, or in very hot conditions.

Do Carbohydrates Make You Fat?

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By Eirik Garnas

“To learn about health, one must study health”
– Albert Einstein

There are few topics in the health and fitness community that are as controversial as carbohydrate consumption. While low-carb dieters sometimes claim that a high carbohydrate intake drives insulin resistance, weight gain and obesity, dietitians and proponents of low-fat diets on the other end of the spectrum often say that everyone should get 40-60% of their daily energy from carbohydrate to fuel the body. In this post I’ll take a step back and look at macronutrient intake in an evolutionary perspective and then discuss carbohydrate consumption in the context of overweight and obesity.

An Evolutionary Framework

What does the basic human diet look like?

When studying macronutrient intake through history it’s natural to start with the human diet during the paleolithic era, which lasted from the earliest known use of stone tools about 2.6 million years ago, up until about 10,000 years before present. Although there is a lot we don’t know about the diet of ancestral populations, it’s well established that our paleolithic ancestors primarily ate fish, meat, eggs, vegetables, fruit, fungi, roots, and nuts. While it’s believed that ancestors of Homo Sapiens evolved into modern humans in Africa, we slowly migrated out into Europe and the rest of the world, and access to fat, carbohydrate and protein depended on geographical location, food availability, and season.


Loren Cordain – the world’s foremost expert on paleolithic nutrition – and colleagues have estimated that our ancestors subsided on a wide range of “paleolithic diets”, but that the most plausible percentages of total energy would be 19–35% for dietary protein, 22–40% for carbohydrate, and 28–58% for fat (1,2). While these numbers have later been questioned by other researchers, it’s widely accepted that paleolithic diets were typically higher in protein and lower in carbohydrate than are current western diets or dietary guidelines. Hunter-gatherers also consumed the most nutrient dense parts of the animal and would therefore have a moderate-high fat intake when possible.

Although hunter-gatherers certainly ate a nutrient-rich diet, this doesn’t imply that we necessarily have to emulate the eating habits of our paleolithic ancestors to be healthy. However, it does provide us with a useful framework for understanding the mismatch between the basic human nutritional template and the modern diets consumed in the world today. Even the most hardcore paleo advocates recognize that the paleo diet has to be tailored to the modern environment and often acknowledge that grass-fed dairy, red wine and some other foods unknown to the paleolithic man can be a part of a healthy diet.

Agricultural revolution

The advent of agriculture about 10,000 years ago marks the beginning of a substantial shift in the human diet. Up until this time, humans had subsided primarily on wild foods, but we now began domesticating plants and animals (3,4).

The first agricultural revolution is sometimes blamed for introducing harmful food into the human diet, and proponents of the paleo diet often claim that our genetics haven’t changed much since the paleolithic era and that we therefore haven’t had enough time to adapt to “neolithic foods”. This premise is highly debated among scientists, and we have also learned that although our human genome changes fairly slowly, the “second” genome in our body – the human microbiome – can be altered fairly rapidly. Micro-organisms in our body provide metabolic functions that stretch far beyond the capabilities of the human host and can adapt to break down a wide range of food ingredients. Both lactose intolerance and gluten sensitivity are often classified as permanent conditions, but the fact is that bacteria in the gut can provide the needed enzymes to break down lactose and are also able to degrade harmful gluten peptides.

Although archaeological data show that the adoption of grain-based diets coincides with a shortening of stature and increased incidence of tooth decay (5), we know that several cultures have maintained good health with cereal grains, legumes and dairy as staple foods, and this suggests that introducing “neolithic foods” in the human diet isn’t necessarily problematic.


Weston A. Price was a dentist that travelled the world during the 1930′s visiting populations that were cut off from the western world. Dr. Price primarily wanted to investigate the oral health of people still eating traditional human diets, but he quickly learned that dental arch deformities and tooth decay are just symptoms of overall poor health. The primitive peoples he visited had very low incidence of non-communicable disease as long as they ate “natural”, unrefined food, but their health quickly detoriated when they moved and began eating refined flours, vegetable oils, sugar, and other western foods. Some of the non-westernized societies Dr. Price visited didn’t even have a name for cancer, and although they made little efforts to maintain good oral hygiene, dental cavities were virtually absent (6).

While the work of Dr. Weston A. Price has several shortcoming, it does show that humans can be lean and healthy on a wide range of diets and macronutrient intakes. Traditional people such as those in the Lötschental Valley in Switzerland, and the Scottish and Gaelic living in the Outer Hebrides relied heavily on grains as staple foods, while other non-westernized societies got more of their energy from fat. His work also suggests that part of the problem with grain consumption in the modern world is that we’re no longer taking the time to neutralize some of the potentially harmful components found in grain fiber (e.g., gluten, lectins) through traditional processing techniques such as soaking, sprouting, and fermentation.

Humans can be lean and healthy on a wide range of macronutrient ratios

Several other researchers have also documented the health of non-westernized people that are lean, healthy, and fit on diets with widely different macronutrient compositions (7):

  • The Kitavans on the Trobriand Islands (8,9)
    One of the last populations on Earth with dietary habits matching that of our paleolithic ancestors.
    – Diet: Root vegetables, fruits, vegetables, fish, and coconuts.
    – Macronutrient ratio: 69% carbohydrate, 10% protein, and 21% fat.
  • The New Guinea Highland Tribe at Tukisenta (10)
    One of the cultures with the highest documented carbohydrate intakes.
    – Diet: Mostly sweet potatoes.
    – Macronutrient ratio: 94 percent of their calories as carbohydrate.
  • The Inuit inhabiting the arctic regions of Greenland, Canada, and the United States (11,12)
    Hunter-gatherers with a very low carbohydrate intake.
    – Diet: Mostly seafood and birds.
    – Macronutrient ratio: About 75% fat, 20% protein, and 0-5% carbohydrate.

While the average lifespan of humans today is probably higher than in any other part of human evolution, it’s clear that several factors such as decline in infant mortality, lower rates of infectious disease, and pharmaceutical use must be considered when comparing life expectancy (13).

The human energy homeostasis functions well in the absence of western food

The energy homeostasis system in our body regulates body fatness and energy balance on a long term basis. The increased rates of overweight and obesity in affluent nations have led to the general belief that this homeostatic system is maladapted to food excess and a sedentary lifestyle, and people are therefore advised to exercise more and to count calories in an attempt to overcome the shortcomings of the thermostat in our body.


However, the fact that non-westernized people such as The Kitavans are lean and healthy despite an abundance of food and with only a moderate amount of exercise, suggests that the energy homeostasis system functions properly when we live in the right ecological niche, eat simple whole-foods, and avoid westernized foods such as grains (refined?), sugar, and vegetable oils (14).

What can the diets of healthy societies teach us about human nutrition?

Although looking at protein-, fat- and carbohydrate intake in hunter-gatherer societies and healthy non-westernized populations only gives us hints about the “optimal” macronutrient ratio and diet in terms of weight loss, health, and longevity, it does provide a useful framework for understanding human nutrition because we learn the following:

  • The transition from eating “natural”, nutrient-rich whole foods to eating highly-palatable, western food is associated with weight gain and a rapid decline in health.
  • Humans can be lean and healthy on a wide range of macronutrient ratios.
  • The energy homeostasis system seems to function properly when we eat “simple” foods such as meat, fish, vegetables, legumes, and fruits.
  • The types of carbohydrate, protein and fat probably tell us more about the healthfulness of the diet than the macronutrient composition in itself.

Why Do We Overeat?

Statistics show that energy consumption in the U.S. has increased from 3,100 kcal/day in 1965 to 3,900 kcal/day in 2012 (15), and although this is on the extreme end of the spectrum, similar trends are seen around the world and especially in affluent nations. It’s no doubt that overweight and obesity are caused by an imbalance between energy intake and energy expenditure, but this doesn’t tell us anything about why we overeat, how the different macronutrients impact our body, and the mechanisms that lead to weight gain. Are gluttony and inactivity really the only reasons why we get fat?

The amount of body fat we carry is regulated by the brain

Just like our body tries to keep things like blood pressure and concentration of ions within a certain range, scientists have known for more than a century that the amount of body fat we carry is regulated by areas in the brain. We essentially have a fat mass “setpoint” that the brain defends through a number of mechanisms, such as increasing or decreasing hunger and metabolic rate (16,17).

A study published in the American Journal of Clinical Nutrition clearly illustrates the idea behind the body fat setpoint. They gave lean and overweight subjects a diet that contained 50% more calories than they naturally consumed, and as expected, all of the participants gained a significant amount of weight during the six weeks of overfeeding. The brain tried to “defend” the body fat setpoint by increasing metabolic rate and body heat production, but these compensatory mechanisms can only prevent a certain degree of fat gain. The interesting thing happened when the overfeeding phase was over and subjects were allowed to eat as much as they wanted for the following six weeks. All of the participants lost the majority of the weight they had gained although they didn’t restrict calories (18).

Other overfeeding studies both in humans and animals have shown the same thing, subjects lose most of the weight when they are no longer overfed and usually stabilize at the same, or a slightly higher setpoint than before.

These mechanisms also apply to underfeeding. Yes, off course we lose weight by consuming less energy than we expend, but the brain signals to increase energy expenditure and hunger, and we usually gain most of the weight back as soon as we’re no longer restricting calories. We’re basically fighting the body instead of working with it. These poor long-term results are seen again and again in scientific trials, but some dietitians and personal trainers still cling to the idea that we just have to exercise more and eat less (of the same food) to permanently shed the fat.

While conscious calorie restriction is necessary for someone who is already lean and wants to go down to single digits of body fat (male), it’s not a long-term solution for those that are overweight and obese. What we really have to do is acknowledge that fat mass is homeostatically regulated and look for the mechanisms that cause overeating and elevated fat setpoint. To permanently shed the fat we have to address the factors that cause the body to want to store more weight! Only then can we design a diet that allows us to lose weight without chronic calorie restriction and hunger.

A breakdown in the signaling system between fat cells and the brain causes us to overeat and store fat

Several theories have been proposed as to why the setpoint is elevated in overweight and obesity, and signaling hormones seem to play an essential role. Leptin is a hormone that’s produced by fat cells in the body and allows the brain to monitor the size of the fat stores by varying appetite and energy expenditure. The fact that leptin production correlates with the size of the fat stores would suggest that overweight and obese people produce more leptin and that the brain should respond to these signals by reducing appetite. However, obesity is characterized by leptin resistance, a condition where leptin produces a smaller response at the receptors in the brain. The brain has essentially become resistant to the signals from leptin and “believes” that the body carries much less body fat than it actually does (19,20).


In general, most westerners have leptin levels that are many times higher than non-westernized people eating “ancestral” diets (14,21). One of the reasons people who are overweight and obese have an elevated fat mass setpoint is that the feedback signal from the fat tissue only partially gets to the hypothalamus in the brain. So, the brain triggers hunger and decreased energy expenditure in an attempt to increase fat storage, boost leptin production, and overcome leptin resistance.

Although a lot of the underlying mechanisms associated with an elevated fat-mass setpoint and increased circulating leptin concentrations aren’t fully established, we do know that inflammation in the brain plays an essential role.

As I talked about earlier, the energy homeostasis system in our body seems to function properly when we eat “simple” foods such as meat, fish, fowl, vegetables, and eggs. This is clearly seen in non-westernized populations where overweight is rare and obesity is unheard of, and suggests that it’s not the brain’s hard-wired mechanisms for regulating hunger and energy expenditure that are not functioning properly, but rather that some aspects of our modern lifestyle dysregulate the energy homeostasis system. Diet seems to be the most important factor involved, and although carbohydrates per se aren’t necessarily problematic, specific types of carbohydrates play an essential role in this whole process of inflammation, leptin resistance, weight gain, and elevated body fat setpoint.

How is that some types of carbohydrates can make you gain weight?

Here I’ll briefly discuss some of the common hypotheses and established facts regarding carbohydrates and weight regulation.

Hypothesis: Carbohydrates are fattening because they elevate insulin and insulin causes fat storage

Most of the carbohydrates we eat are broken down into glucose in the body and then absorbed into cells with the help of a hormone called insulin. Simply put, the insulin hypothesis basically states that carbohydrates (especially refined carbs) elevate circulating insulin and that insulin drives us to store more fat. I’m not going to spend a lot of time discussing the hypothesis for the following reasons:

  1. It doesn’t account for the fact that several cultures remain lean even with a high carbohydrate intake and little food shortage.
  2. Several other writers have written extensively about the hypothesis.
  3. There’s a lot of conflicting evidence in the scientific literature (22,23,24).
  4. Obesity researchers are not onboard with the insulin hypothesis of obesity and consider insulin resistance to be a consequence, not a cause, of fat gain.

Bottom line: Insulin does play a role in the modern obesity epidemic, and the fact is that most people in the modern world aren’t as metabolically healthy as non-westernized people eating traditional diets, but to suggest that all carbohydrates are bad because they elevate insulin makes little sense.


Hypothesis: Carbohydrates are fattening because we aren’t as active as before and therefore don’t need as much glucose

Regular physical activity is associated with several improvements in health, and resistance training is great for building the body. When we lived as hunter-gatherers we typically had to expend a fair amount of energy to get the food we needed, and the cost to obtain energy was therefore much higher than it is today. Since physical activity increases energy expenditure it’s often believed that regular exercise is beneficial for weight loss. However, the brain homeostatically guards the fat mass we carry, and many of people compensate for the increased energy expenditure during exercise by eating more and/or being less active during the rest of the day (25).

The fact is that exercise doesn’t burn that many calories compared to what is achievable through diet, and although physical activity can influence body weight through several other mechanisms, such as decreasing low-grade chronic inflammation and improving insulin and leptin sensitivity, studies show that for most people, exercise alone is not a very effective strategy for losing weight (25).

The fact that several cultures with a high carbohydrate intake are fit and healthy even though they aren’t especially active also supports the notion that we don’t necessarily have to exercise to be lean.

While it’s often believed that we are less active today than in any other part of human evolution, statistics show that physical activity expenditure has not declined over the same period that obesity rates have increased dramatically (26).

Bottom line: Although physical activity improves our metabolic health and allows us to consume a larger amount of energy and carbohydrates without getting fat, studies show that for most people, isolated anaerobic or aerobic exercise is not very effective for losing weight.

Hypothesis: We overeat because we consume too much carbohydrate and too little protein

The Protein-Leverage Hypothesis (PLH) suggests that humans regulate their intake of macronutrients and that protein is prioritized over fat, carbohydrate, and total energy intake. The notion that animals and humans have a target protein intake and continue eating in an attempt to reach this setpoint, actually has a fair amount of support in the scientific literature. Sources of carbohydrate and fat such as vegetables, grains and vegetable oils are cheap compared to high-quality meat, seafood, eggs, and grass-fed dairy, and protein is therefore often substituted for the other two macronutrients.

The western dietary pattern is characterized by high intakes of refined flours, vegetable oils, and sugars, and although meat and dairy products are usually a part of the diet of most westerners, modern diets are typically lower in protein and higher in carbohydrate compared to the diet we have been eating through most of human evolution. It’s estimated that our hunter-gatherer ancestors got between 19-35% of their energy from protein, while the average protein intake in the U.S. today is around 15% (27).

A recent randomized controlled study in humans showed that subjects eating a diet with 10% protein had a higher total energy intake compared to participants eating 15% or 25% protein, but that increasing protein from 15% to 25% did not alter energy intake (28). This would imply that the protein intake in the “western diet” is sufficient to avoid overconsumption of fat and carbohydrate. But, the skyrocketing rates of overweight and obesity in westernized countries suggest that people routinely consume more energy than they expend and that the percentage of protein in the diet therefore reflects protein intake on a diet that contains more food than we need to sustain bodyweight. So, although the daily excess energy intake isn’t a lot, one of the reasons we consume more food could be because we’re aiming for a targeted protein intake…

A recent review of 28 experimental trials shows that percent dietary protein in the diet is negatively associated with total energy intake regardless of fat and carbohydrate content of the diet, and strongly supports a role for protein leverage in lean, overweight, and obese humans (29).


Another study from 2012 also shows that body-weight loss and weight-maintenance on a low-carbohydrate diet seems to depend more on the protein consumption than the carbohydrate intake (30).

Bottom line: Protein is a very satiating macronutrient, and studies show that a low protein intake can lead to overeating.

Hypothesis: “Toxins” in carbohydrate-rich foods such as grains and legumes promote inflammation and weight gain

One of the basic premises of the paleo diet is that the first agricultural revolution introduced “toxic” food ingredients such as lectins, gluten and phytic acid into the human food chain. Both plants and animals have their own defense system that protects them from invading predators, and while fish and land mammals are able to flee, hide or fight, plants develop secondary metabolites that protect them against pathogens and herbivores. These secondary metabolites are either benign, toxic, antinutritional or somewhere in between, depending on the animal that eats them and the quantity in which they are consumed.

“Neolithic foods” are especially rich in antinutrients, and one of the reasons paleo advocates argue that humans should avoid cereal grains, beans and white potatoes is that we haven’t had adequate time to develop resistance to antinutritional compounds that interfere with the absorption of nutrients and possibly cause other harmful effects in the body.

The toxic effects of secondary metabolites seem to depend on the antinutrient in question, how much we ingest, and how well we tolerate these compounds. There’s a lot of debate regarding the harmful effects of antinutrients, and although animal models show that phytic acid, lectins and protease inhibitors can disrupt normal gut physiology, the available data in humans are scant (31,32,33). Some researchers have proposed that the human leptin system isn’t adapted to a cereal-based diet and that lectins in grains could cause leptin resistance (34), but more research is needed to know if there is a connection between secondary metabolites such as lectins and weight gain.

However, we do know that grain-related disorders such as celiac disease and gluten sensitivity are on the rise and that gluten can be problematic even in people without celiac disease (35,36).

One of the problems with whole grains in the western diet is that we no longer remove or deactivate antinutrients by using traditional food processing techniques. Healthy grain-based cultures usually soak, grind and/or ferment cereal grains to remove or deactivate many of the defensive substances found in grain fiber.

Bottom line: Many people experience better digestion and health when they remove wheat and other cereal grains from their diet, and this probably has to do with a sensitivity to proteins and secondary metabolites in these foods. Using traditional food processing techniques make grains and legumes more nutritious and easier to digest.
We need more human studies to say anything concrete about the connection between antinutrients, human health, and weight regulation.

Hypothesis: Refined carbohydrates change the balance of bacteria that live in the gastrointestinal tract and cause inflammation and weight gain

In my last guest post at I talked about the trillions of microorganisms that live in and on the human body and how imbalances (dysbiosis) in the microbial communities can initiate a vicious cycle of increased intestinal permeability, inflammation, and weight gain. Bacteria in the body provide a wide range of metabolic functions that stretch far beyond the physiological capabilities of the human host, and one of the primary jobs of the microorganisms in our digestive system is to break down indigestible (to the human host) food components. While most of the critters live in the large intestine, we also have bacteria in the mouth and small intestine, and the composition of microbes throughout our gastrointestinal tract depends on several factors such as diet, hygiene, and pharmaceutical use.


Plant foods such as vegetables, tubers, fruits, and functional plant parts store their carbohydrates in living cells that stay largely intact during cooking and are first breached during the digestive process. These fiber-walled living cells only allow for a maximum density of around 23% non-fibrous carbohydrate by mass, which explains why “ancestral” sources of carbohydrates such as fruits and vegetables have a relatively low-carbohydrate density compared to the most common sources of carbohydrate in the western diet (14).

Flour, sugar and processed plant foods don’t have this cellular storage and contain a considerably higher percentage of carbohydrate than anything else we have been eating throughout our evolutionary history. These “acellular” carbohydrates are essentially already broken down through the production process and provide an evolutionary unprecedented high concentration of carbohydrates in the semifluid mass of partly digested food that pass from the stomach into the small intestine.

It’s well established that a high intake of refined carbohydrates increases the growth of harmful bacteria in the mouth and often produces tooth decay. A new hypothesis of obesity suggests that dense sources of carbohydrates such as sugar and flours (possibly also whole grains) change the balance of bacteria in the small intestine and that this inflammatory microbiota initiates leptin resistance, weight gain, and obesity (14).

We also know that people frequently substitute fruits, vegetables and nuts for processed foods containing refined grains and/or sugar and therefore consume less dietary fiber. Some types of dietary fibers – prebiotics – are utilized by beneficial bacteria in our digestive systems, and a lack of these fermentable substrates can also be a part of the reason why obesity is characterized a dysbiotic gut microbiota (37).

All the microorganisms that live in the human body – the human microbiome – don’t only impact our physiological health, but also influence our mood, behaviour, and thoughts. This is relevant in terms of carbohydrates and weight gain, because gut bacteria could play a role in controlling our appetite (38). So, when our gut microbiota changes due to a high intake of highly dense (acellular?) carbohydrates and/or by a lack of prebiotic fiber, it could affect the food preferences of the human host through a positive feedback loop. It might sound far-fetched that the microorganisms in our body can influence the preferences of the host for a particular dietary regime to their own advantage, but the fact is that we are actually 99% microbe from a genetic perspective and that this microbial rainforest impacts most aspects of both our physiological and mental health (39).

Bottom line: The trillions of microbes that live in and on the human body play an essential role in regulating our body weight, and overweight and obesity is characterized by imbalances in the microbial communities. Refined carbohydrates (and possibly even whole grains) and a low intake of prebiotic fiber could drive weight gain by promoting dysbiosis, inflammation, and insulin and leptin resistance. A recent hypothesis suggests that this is a self-sustaining cycle where highly-dense sources of carbohydrates promote the growth of proinflammatory microorganisms in the gut and that these microbes increase our satiety for substrates that benefit their growth and survival.

Refined carbohydrates in the form of highly palatable and/or rewarding foods promote overeating and an elevated body fat setpoint

The brain has it’s own value/reward system that reinforces or discourages certain types of behaviors. For example if we burn ourselves on a hot stove we quickly learn that the reward value of that behavior is low, and we probably won’t do it again. On the contrary, if we eat foods that are rich in rewarding qualities such as fat, starch, sugar and salt, we learn that these foods are safe, palatable and possibly energy-dense, and we’re motivated to seek out these products again and again.

The problem is that the reward system evolved to deal with natural environmental stimuli. When we lived as simple farmers and hunter-gatherers it motivated us to seek out nutrient-dense sources of energy to be able to survive and store fat for scarcer times. However, in affluent nations we now have access to an abundance of food, and food manufacturers hire scientists to design products with the most rewarding and palatable combination of fat, starch, salt, glutamate, and sugar. Compared to fruits, nuts, vegetables, and meats, modern processed food is hyper-rewarding in the sense that it contains a broad spectrum of reward factors that aren’t found in “natural”, whole foods. Some people essentially become “addicted” to fast food (40).

One of the most interesting studies on food reward in humans was published in 1965 and involved feeding lean and obese humans through a liquid feeding device. Participants were allowed to eat as much of the liquid food as they wanted, but couldn’t consume anything else. While lean subjects ate their normal amount of energy and maintained body weight, obese subjects lowered their food intake dramatically, and although they only ate between 200-300 calories a day (yes, you read that right), they didn’t experience fatigue or hunger, and quickly started losing massive amounts of weight. It seemed like their bodies responded to the monotonous, low-rewarding diet of liquid food by lowering the body fat set point and increasing the use of stored body fat for energy (41).

The brain’s mechanisms for regulating food intake and body fatness aren’t sufficient to protect against processed western food. It seems that highly-rewarding food can increase the body fat setpoint in susceptible people and cause abnormalities in the parts of the brain that regulate metabolism, fat storage, and reward (42,43,44,45).

Many obesity researchers now consider the food reward hypothesis to be a dominant factor in the modern obesity epidemic.

Paleo Diet

Highly-palatable and energy-dense foods typically contain little water, fiber and protein, and are therefore less satiating per calorie compared to simple, unprocessed foods such as root tubers, nuts, and fruits (46). This is probably one of the reasons why many people unconsciously eat fewer calories when they start eating a diet based on nutrient-rich, whole foods – they feel fuller on less energy.

Sucrose, commonly know as table sugar, is made up of the simple sugars glucose and fructose. While a healthy human body can handle a significant amount of glucose, excessive consumption of fructose from juice, sweetened beverages and other processed foods is linked to leptin resistance and weight gain (47,48).

Bottom line: One of the problems with sugar, flours, and other refined sources of carbohydrate is that they are commonly found in processed foods that also contain plenty of fat, salt, and glutamate. These foods are engineered to be palatable and rewarding in the sense that we seek them out again and again. Western foods such as sweetened beverages and biscuits are less satiating than simple, whole foods and often contain sugars such as fructose that can be harmful if eaten in excess.

Why do studies show that low-carb diets are superior to low-fat diets for weight loss?

A common practice employed by proponents of a low-carbohydrate eating style is to cite some of the numerous studies which show that diets with a relatively low percentage of carbohydrates (typically 5-20% of daily energy from carbs) are superior to low fat diets (40-60% energy from carbs) for weight loss.

The majority of studies show that when participants are allowed to eat as much as they want (ad libitum) from either a low-carbohydrate or low-fat diet, subjects in the low-carbohydrate group unconsciously reduce their energy intake and lose more weight than those in the low-fat group (49,50,51).

However, in energy restricted trials where participants are instructed to eat the same amount of calories from either a low-carbohydrate or low-fat diet, they lose an equal amount of weight (52,53,54). This indicates that if there is a “metabolic advantage” to low-carbohydrate diets, it’s quite small.

The fact is that these studies tell us little about the underlying mechanisms and why carbohydrate restriction is beneficial on an ad libitum diet. Is it the macronutrient intake in itself that regulates satiety, total energy intake and fat storage, or are there other factors involved? Why do people who eat low-carbohydrate diets tend to reduce their energy intake?

If you’ve read this entire post you can probably answer that question by now, and just to recap, here are some of the reasons why people tend to unconsciously reduce their energy intake – indicating a lowered body fat setpoint – when they start eating a low-carb diet:

  • Low-carbohydrate diets are typically higher in protein than low-fat diets due to an increased intake of animal products.
  • Low-carbohydrate diets are typically low in gluten and secondary metabolites associated with whole grains.
  • Low-carbohydrate diets typically contain little refined grains and sugar.
  • By limiting the amount of starch and sugar in the diet you remove two of the most rewarding properties of food, and it’s therefore no surprise that a lot of people reduce their total energy intake when they adopt a low-carbohydrate eating style. Since many processed, westernized foods contain a fair amount of starch and sugar, low-carbohydrate dieters are typically “forced” to eat more whole, unprocessed food.



  • Humans can be lean and healthy on a wide range of diets (not the western diet), as long as we eat the right types of food.
  • The system in our body that regulates long-term fat storage seems to function properly when we live in the right ecological niche and eat “simple”, whole foods.
  • Carbohydrates per se aren’t fattening, but specific types of carbohydrates – in the right context and amount – are.
  • There is a mismatch between the sources of carbohydrates we are adapted to eat and the ones that make up most of the western diet.
  • Chronic conscious calorie restriction is not the way to go for long-term weight loss. Rather, we should work with the body by designing a diet that helps us eat less without going hungry all the time. However, someone who is already lean and wants to lose even more weight (e.g., down to single digits of body fat percentage for males) will usually have to make a conscious attempt to reduce food intake, because that level of bodyfat is below what is considered optimal for survival and reproduction, and the brain therefore protects fat mass by increasing hunger and decreasing body heat production and metabolic rate.
  • Exercise usually isn’t very effective for weight loss since most people compensate – at least partially – for the increased energy expenditure by eating more food. However, regular physical activity also impacts our metabolic health by improving leptin and insulin sensitivity and allows us to tolerate a higher amount of calories and carbohydrates in the diet without gaining weight.
  • The things that we would do to prevent and treat overweight are just the things that we need to be doing to promote overall good health.

Some strategies to lower the body fat setpoint and lose weight

  • People living in affluent nations often aren’t as metabolically healthy (e.g., impaired glucose tolerance, insulin resistance) as non-westernized people eating “ancestral diets”, and therefore benefit from reducing the overall carbohydrate intake of the diet. Official dietary guidelines indicate that we should all be eating between 45-55% of calories from carbohydrate, but this is probably on the high side for most people.
  • Refined grains and (added) sugar should be avoided.
  • Traditional food processing techniques such as soaking and fermentation make whole grains and legumes more nutritious and easier to digest.
  • Carbohydrates as part of highly-palatable and/or rewarding foods are especially problematic as these products often promote overeating and weight gain.
  • Eat a nutrient-dense diet composed primarily of whole foods such as meat, fish, fowl, eggs, vegetables, root tubers, grass-fed dairy, legumes, and fruits.
  • Take care of the trillions of microorganisms in your body by eating probiotics and prebiotics.
  • Do some type of regular exercise to increase muscle mass and improve metabolic health.

Sitting, standing, or walking: What’s the best way to work?

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We sit to commute. Sit at our computers. Sit at meetings. Relax…by sitting at home. In North America, most adults sit for about 9.3 hours. And that’s bad news for our health.

When we sit for long periods, circulation is constricted. Metabolism slows. Muscles shut off; connective tissue tightens.

Our brain hungers for blood and nutrients that are barely slugging through our system.

Our body engine is set to “idle”, neutral, or even worse — switched off.

Sitting too much makes us unhealthier, unfitter, more metabolically broken — possibly even dumber.

Ha, you think. I work out. I’m safe.

Think again.

If you work out for an hour a day, but sit for the remainder, that one hour doesn’t do much to counter 9+ hours of butt-in-chair.

(Just like running an hour doesn’t give you a free pass to smoke.)

Bottom line: There is nothing good about prolonged, chronic sitting.

So what can you do?

Well, throughout the health and ergonomic world, experts have proposed:

  • Sitting on an exercise ball rather than a chair.
  • Working at a standing desk rather than sitting.
  • Using a treadmill while working at a standing desk.
  • Breaking up sitting with movement at regular intervals.

These all sound good.

But do any of them actually make a difference?

Let’s take a look.

The quest for a better chair

The biggest problem with sitting down all day: It’s uncomfortable.

Sore backs. Stiff necks. Aching shoulders. Throbbing knees.

(In fact, the prolonged contact between femur and patella that can cause chronic knee pain is often called “moviegoer’s knee”.)

If we’re at a computer, we slouch. Lean in further towards the screen. Round our shoulders forward. Crane our necks. Squint. Tense our facial muscles.

And like the loyal suspension bridges they are, our backs try to compensate valiantly.

In as little as an hour of sitting, our backs can measurably stiffen.

(Men suffer slightly more than women, who are typically a bit more flexible.)

Not surprisingly, designers have tried to build a better chair. And over the last decade, researchers have compared the various options.

iStock 000014201516Small Sitting, standing, or walking: Whats the best way to work?

Balls vs. chairs

One common alternative to the standard office chair is the exercise ball.

The theory behind the exercise-ball-chair is that the unstable surface will keep the back muscles working.

This is assumed to be a Good Thing.

Turns out, not so much.

First of all, studies show that spinal compression and muscular activation is pretty much identical whether using a chair or using a ball as a seat.

Indeed, the greater contact area of the ball compared to a chair might encourage more soft tissue compression, which can mean more discomfort, soreness, and numbness.

Related work looking at muscle activation in the rest of the body found that subjects moved their trunks more on the ball than chair, yet they also experienced more “spinal shrinkage” (discs being compressed) and more trapezius activation (upper back and neck stiffening).

These drawbacks may outweigh any potential benefits.

Dynamic chairs vs. standard chairs

So the exercise ball may not be such a great idea. But balls aren’t the only kind of dynamic chairs on the market.

For instance, some office chairs allow the seat pan to move as the back tilts. How do these stack up?

In looking at three of these kinds of chairs compared with a typical static office chair, one study showed that the real issue doesn’t seem to be how the chair affects muscle activation, but rather, how different kinds of tasks affect activation.

In other words, the sliding seat pan doesn’t make a whole lot of difference.

Kneeling chairs

OK, how about those funky-looking kneeling chairs?

There’s not a lot of research on this type of chair.

One paper considered what type of chair maintains a “proper” lumbar curve. Unfortunately, the study only looked at posture comparisons between standing and sitting using a chair or a kneeling chair.

No tasks were assessed; no muscle activation checked, no spinal shrinkage measured. So in the end, it doesn’t really tell us much.

Another study looked at self-induced movements in kneeling vs. regular chairs. It showed that on the kneeling chair, the lower body is “turned off” when prepping for movements, which may actually reduce balance and function.

The bottom line for your bottom and back: task awareness

The best option: When you have to sit, sit on something that:

  • reduces pressure on the body;
  • reduces points of contact with soft tissue;
  • reduces tension; and
  • reduces the stress of tasks like typing or writing (or reading or filing or phoning).

But that’s not a perfect solution.

No matter we’re sitting in or on, within a short time the negative effects of sitting are going to bite us in the bum.

Balls and kneelers don’t seem to be better. In fact, in some ways they might be worse than well-designed chairs.

But even with well-designed chairs, our bodies have different needs with different tasks. We need to respond effectively to those tasks.

We’ll come back to that shortly.

From musculoskeletal to metabolic

So when it comes to muscle activation, spinal shape and spinal compression, all chairs are pretty much equal, with small tradeoffs between them.

But how does sitting affect metabolism?

Key point: “Uninterrupted sedentary time” is strongly associated with “cardio-metabolic and inflammatory risk biomarkers” — regardless of age, gender or ethnicity.

In other words, sitting sucks. For everyone.

And if we sat less, we would be leaner, healthier people.

Sitting: as bad as smoking?

Indeed, a study that looked at 105 full-time office workers showed that those who sat longer were about three times as likely to have a waist circumference larger than 94cm (37 inches) for men or 80cm (31 inches) for women.

Waist circumference, as you probably know, is strongly associated with cardio-metabolic risk.

These same workers were also nine times more likely to have a BMI greater than 30, which in technical terms would make them obese.

Meanwhile, another study showed that each additional hour of sitting led to larger waist circumferences, as well as higher insulin and lower HDL cholesterol. Not good.

In fact, the evidence against prolonged sitting is so strong that one paper asks if chronic sitting, in itself, ought to be considered a “distinct coronary heart disease risk factor”.

That’s putting prolonged sitting in the same category as smoking.

Given these correlations, the comparison may not be surprising.

standing Sitting, standing, or walking: Whats the best way to work?

Stand up!

If sitting sucks regardless of the throne we choose, is standing any better?

One study suggests that computer users who spend as little as one hour a day on their feet at work have less back pain.

Interestingly, data entry speed went down when standing, but not by a lot.

By the way, these tests were performed with people who had not practiced standing desk work. With practice, they’d probably get better at it.

So, when it comes to aches and pains, standing may be a good alternative to sitting.

But will people actually use the option to stand if it’s available?

It appears they will.

A Swedish call center with over one hundred employees adopted sit-stand desks and found that people stood more and sat less.

A recently reported Australian study explored the same issue. With electronically or manually adjustable sit-stand desks available, sitting time at work went from 85% at start to 60% by the time the study ended.

Interestingly, participants were motivated to give the desks a try, either because of their own “dodgy backs” or because they’d heard they could burn more calories standing up.

Other studies have looked at the effects of sit-stand desks on metabolic markers of health and disease, and found that short bouts of light to moderate intensity walking lowered post-meal glucose and insulin levels in overweight and obese adults.

Granted, these studies considered movement vs. sitting rather than standing vs. sitting. But standing, it turns out, can be a pretty good substitute for and complement to movement.

Whether standing or walking, what’s most important is reducing overall sitting time.

By the way, those Australian office workers were right. Standing burns about 1.36 Kcals per minute more than sitting. That’s more than sixty calories an hour. Multiplied by eight (the hours in a typical work day) and you’re talking about 500 calories or more a day.

Big difference. If you’re looking to lose weight or simply stay lean, get out of your chair ASAP.

What about walking desks?

If standing is good, and walking is good, what about combining them in a walking desk?

Great idea. Standing takes more energy than sitting. And walking takes more energy than standing.

It sounds like a slam-dunk. Walk all day at work, lose weight, reduce musculoskeletal pain, and improve metabolic function. Bingo!

But hang on. Is anyone actually able to get any work done with these walking desks?

After all, there’s a reason that most of us sit on the job. Our work requires sustained attention to detail, analytical focus, creativity, innovation, or discovery.

Is any of that possible with a moving desk?

walking desk Sitting, standing, or walking: Whats the best way to work?

Sit down and think it over

In other words, before we all get carried away and sink our hard-earned dollars into standing or walking desks in an effort to save our backs or to boost our metabolism, we also need to consider another critical variable: cognitive performance.

Humans do tend to do finer work sitting down, and this has been true for thousands of years. It’s hard to imagine the creators of cuneiform tablets breezily jotting down their little notches in clay while at a brisk trot.

So if we’re doing some heavy-duty thinking, reading, or writing, is it better to sit?

It appears so.

In our own research, we looked at whether people perform better cognitively when seated or when standing. We wanted to understand whether the indisputable metabolic benefits of standing might also apply to the cognitive realm.

Alas, the answer appears to be no.

On the positive side, there was little statistical difference in cognitive performance between standing and sitting. In other words, if you feel better standing rather than sitting, it won’t hurt your brain power a whole lot if you decide to stand.

However, there was one important exception.

Those who need to multi-task do better when they are seated.

To that end, we’d now like to test a responsive sit-stand desk, one that could detect multitasking and gently descend to help people achieve a better position for this work. But this research remains in the future.

As for the walking desk, it seems those metabolic benefits come with a cognitive cost, and the cost goes up as the level of mental challenge increases.

In other words, the tougher the task, the more mistakes you’ll make if you’re trying to perform it on a walking desk.

This result is not entirely surprising.

Work on walking and task performance consistently shows that participants slow down and finally halt – sitting down to work out problems as the challenge increases.

Not so fast: movement and cognitive performance

So, in the interests of working smart, should you just forget about the walking desk and go back to slumping over your screen? Not so fast.

Because even if walking desks can interfere with task performance on the job, movement itself is hugely beneficial to overall cognitive function.

Cognitive research shows that people who are regularly active perform better throughout their lives than their peers who don’t.

And it’s never too late to start a movement practice. More and more studies are demonstrating that even short spurts of exercise (say, 20 minutes long) improve cognitive performance immediately afterwards in people of all ages.

In other words, exercise first, then go be smart, rather than trying to walk and solve equations at the same time.

I can see clearly now – or not?

Movement is also critical for another part of our well-being: vision.

For most of us, vision is the primary way we experience the world.

Unfortunately, myopia (or nearsightedness) has been increasing globally. While there is some debate about the causes, lower visual acuity seems connected to more screen time.

Screen work focuses our eye muscles in a particular position for long periods, while preventing them from focusing at other distances, as they are designed to do.

In other words, myopia may be a kind of repetitive strain injury of the eyes.

When we don’t see well, we don’t perform well.

These cognitive and physical effects have been studied extensively in sports. We’re just starting to apply that research to the realm of knowledge work.

Just as movement throughout our day can aid in clearer thinking and reduce the strain on our musculoskeletal and metabolic systems, it might also reduce visual strain inherent in seated, static-posture computer work.

It’s not about the chair

Fundamentally, research on physical well-being and cognitive performance all comes back to this:

Movement is good for us — for everything about us. And lack of movement leads to disease.

Sitting all day is just bad for us as human beings.

A ball chair, or a better chair, or a stand-up desk are all better than nothing. But let’s push this a step further. Let’s look for different ways of working that will let us perform at our best.

Let’s move more often throughout our days. Let the juices flow. And then, sit (briefly) when it suits us — perhaps for contemplation, or deep concentration.

Get creative

If you’re a seated worker reading this, don’t get discouraged. Get imaginative and strategic.

Think: How can I make this task more active?

Look for options and small, simple changes. You probably have more possibilities than you realize.

Sneak what Frank Forencish of Exuberant Animal calls a “movement snack.”

  • Go on errands. Use the bathroom one floor up. Pop over to another building to get something or meet someone.
  • Brainstorm or plan standing up. Use a whiteboard or a flipchart instead of a pen and paper. Or spread some sheets of paper out on the floor and squat down to organize them.
  • Sit when it’s best to sit. Move when it’s best to move. Figure out how to make rote tasks more active, and how to make intensely cognitive tasks more focused.
  • Experiment to find out what works for you, and remember that combining movement with work improves with practice. Don’t leap on your treadmill desk at 4 mph and try to knock out your PhD thesis. Try just standing up for a little while first.
  • Take regular movement breaks. Set a timer. Every hour, stand up, stretch, walk around for a few minutes.
  • Allude vaguely to a smoking habit or back injury, and get your coworkers accustomed to you popping out for some fresh air, or standing up in meetings (you can easily lean unobtrusively against a wall).
  • Have walking meetings. Outside if possible. Your coworkers will probably appreciate the break too.
  • Walk and talk. When you take a phone call, stand up or go for a stroll. Try a dictation app on your smartphone for jotting down notes. Many apps will even transcribe your speech. Basic accessibility features on most computers and smartphones will read your screen to you. Why not listen to your email while out for a brisk constitutional?
  • Ask for better. Many workplaces offer options for healthier work… but employees don’t ask for them. Start asking. Employers understand cost cutting, and healthier employees definitely save money. A few hundred dollars on a treadmill desk could save thousands in physio costs later.

Bottom line

Improving ergonomics with better chairs or workstations is a great start, and an easy way to make a small, immediate, manageable change.

But simply adapting ourselves to how we think ”work should get done” isn’t enough.

We need to go further, for our own health. For optimal human performance along with creativity, innovation, and quality of life, we need to adapt the environment to our actual needs.

Humans need to move. So let’s get going.

Keeping Fit May Reduce Breast Cancer Risk

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Women who keep fit with regular exercise, even mild physical activity, may reduce their risk of developing breast cancer, even after the menopause, but not if they also put on a lot of weight, according to a new study from the US.

The researchers found that the greatest effect was in women who exercised recreationally 10 to 19 hours a week: this appeared to reduce their risk of developing breast cancer by around 30%.

However, they also found that substantial weight gain can negate this benefit.

They write about their work in a paper due to be published this week in the journal Cancer.

Study author Lauren McCullough, a doctoral candidate at the University of North Carolina at Chapel Hill’s Gillings School of Global Public Health, and colleagues, examined the effect of recreational physical activity, done at different points in life, including after the menopause, on women’s risk of developing breast cancer.

While others have already shown that exercise can reduce breast cancer risk, McCullough and colleagues were interested in some of the questions that still remain unanswered. For example, how much exercise, and how often? Does it have to be intense, or does mild physical activity also have an impact? Does this work for all body types or just some? And does it work for all types of breast cancer?

For this study, they examined data on over 3,000 women aged between 20 and 98 years who took part in the Long Island Breast Cancer Study Project: a multistudy effort that began in 1993 to investigate whether environmental factors are responsible for breast cancer.

About half the women (1,504) had breast cancer, and of these the vast majority had invasive breast cancer (1,271).

The researchers found that:

    • Women who exercised during their reproductive years or during the menopause had a reduced risk for breast cancer.


    • Exercising 10 to 19 hours per week, outside of work activity, was linked to the largest, approximately 30%, reduction in risk.


    • All levels of exercise, from mild to intense, were linked to reduction in risk of the most common breast cancers in American women, the hormone receptor positive (ER and PR positive) breast cancers.


  • However, active women who gained a significant amount of weight, particularly after the menopause, had an increased risk for breast cancer, suggesting weight gain can wipe out the beneficial effect of exercise.

McCullough and colleagues did not examine the underlying reasons for the effect of exercise on breast cancer risk, but suggest it may have something to do with controlling energy balance and obesity, that leads to reduced insulin resistance and inflammation.

They conclude that:

“Collectively, these results suggest that women can still reduce their breast cancer risk later in life by maintaining their weight and engaging in moderate amounts of activity.”

McCullough told the press:

“The observation of a reduced risk of breast cancer for women who engaged in exercise after menopause is particularly encouraging given the late age of onset for breast cancer.”

Written by Catharine Paddock

Tea benefits: weight loss, improved bone health and mood

That moment in the morning when tea drinkers take their first warm sip can be amazing. And now, 12 new articles from the American Journal of Clinical Nutrition show that tea may indeed be a magical elixir, as it was shown to promote weight loss, prevent chronic illnesses and improve mood.

Whether iced or hot, on any given day, over 158 million people in the US drink tea, according to the Tea Association of the USA. And our British counterparts consume 165 million cups daily.

Tea is the second most consumed beverage in the world, according to the Tea Association, beaten only by water. Though there have been a multitude of studies about antioxidants in tea and the resulting human health effects, these recent studies in the American Journal of Clinical Nutrition (AJCN) shed light on just how helpful tea is for our health.

Experts from the US Department of Agriculture, National Institutes of Health, UCLA and the University of Glasgow – among others – contributed to the AJCN body of evidence.

Jeffrey Blumberg, PhD, compendium editor for the issue, says:

“The scientists who contributed their original research and insights are among the best in the world, and together, this body of research has significantly advanced the science of tea and human health.”

Tea and weight loss

2 people drinking tea together
Along with promoting weight loss, studies found that drinking tea reduces cancer and cardiovascular risks and it also provides psychological benefits.

Researchers who looked at polyphenols – natural compounds in tea – found that they, along with the caffeine content, increased energy expenditure and fat oxidation, which resulted in weight loss and helped maintain a healthy body weight.

One study shows that subjects who consumed green tea and caffeine lost an average of 2.9 pounds over 12 weeks, all while maintaining their normal diet.

Other studies show that regular tea drinkers have lower body mass indexes (BMIs) and waist-to-hip ratios, along with less body fat, compared with non-tea drinkers.

Additionally, another review showed that the increase in calories burned as a result of drinking tea equates to around 100 calories during a 24-hour period.

Reduced cancer and cardiovascular risks

Another set of researchers found that the polyphenols in green tea may help to stop the progression of certain cancers.

In one study, scientists observed that after a year, 30% of men in a placebo group progressed to prostate cancer, compared with only 9% of men who were in a tea-supplemented group.

Other cancers for which tea provides protective health benefits are cancers of the gastrointestinal tract, lung, breast and skin, researchers say.

A study conducted by Dr. Claudio Ferri in Italy showed that black tea reduced blood pressure in patients with hypertension and also neutralized negative effects of high-fat meals on arterial blood flow and blood pressure.

Dr. Ferri comments on his findings:

“Our studies build on previous work to clearly show that drinking as little as one cup of tea per day supports healthy arterial function and blood pressure. These results suggest that on a population scale, drinking tea could help reduce significantly the incidence of stroke, heart attack and other cardiovascular diseases.”

Improved bone strength, alertness and problem solving

Another benefit of the polyphenols in green tea includes improving bone quality and strength, particularly in the wake of osteoporosis.

Tea drinking in one study was associated with a 30% reduced risk of hip fractures in men and women aged 50 years or older.

And if that fails to put individuals in a good mood, drinking tea will. In one study in particular, drinking tea was found to improve attention and facilitate better focus on tasks.

Subjects in the study drank 2-3 cups of tea within 90 minutes, and this resulted in more accurate results during an attention task and feelings of being more alert, compared with subjects drinking a placebo.

Researchers note that the amino acid theanine and caffeine in tea are thought to confer psychological benefits to drinkers, strengthening attention, mood and performance.

“Humans have been drinking tea for some 5,000 years, dating back to the Paleolithic period,” says Prof. Blumberg. “Modern research is providing the proof that there are real health benefits to gain from enjoying this ancient beverage.”

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Eat breakfast to improve your heart health

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A new study appears to confirm that when you eat is just as important for health as what and how much you eat.

US researchers asked men to complete questionnaires about what they ate and when they ate it, then tracked their health for 16 years. Those who said they skipped breakfast were found to have a higher risk of heart attack or fatal coronary heart disease.

Lead author Leah Cahill, of the Harvard School of Public Health (HSPH), and colleagues, write about their findings in a July 23rd issue of the American Heart Association journal Circulation.

In a statement, Leah Cahill, who is a postdoctoral research fellow in the department of nutrition at HSPH, explains what may lie behind the findings:

“Skipping breakfast may lead to one or more risk factors, including obesity, high blood pressure, high cholesterol and diabetes, which may in turn lead to a heart attack over time.”

For their study the researchers analyzed food frequency questionnaires completed by 26,902 male health professionals aged between 45 and 82 years and tracked their health for 16 years from 1992 to 2008. The men were free of heart disease and cancer at the start of the study.

Over the follow-up, 1,572 men experienced non-fatal heart attacks or died of coronary heart disease.

When they analyzed the data the researchers found men who said they did not have breakfast had a 27% higher risk of heart attack or death from coronary heart disease than men who said they ate breakfast.

Men who skipped breakfast had other risk factors

The men who said they skipped breakfast tended to be younger, single, smokers, who worked full time, did not do much exercise and drank more alcohol.

The researchers also found when they adjusted the results to take out the effect of body mass index, high blood pressure, high cholesterol and diabetes, the links between skipping breakfast and higher risk for heart attack or death from coronary heart disease became much weaker: they were no longer statistically significant.

They note this suggests “eating habits may affect risk of coronary heart disease through pathways associated with these traditional risk factors.”

They also found no links between how many times a day the men said they ate and risk of coronary heart disease.

Eating late at night linked to heart disease

They did find a link, however, between eating late at night and coronary heart disease. Compared with men who said they did not eat late at night, among those who did, there was a 55% higher risk of coronary heart disease.

But the authors note that, judging by the few men in the study who ate late at night, this was unlikely to be a major public health concern.

Leah Cahill says the message from the study, which reinforces previous research, is: “Don’t skip breakfast.” Eating a healthy meal at the start of the day is linked to lower risk of heart attacks.

Breakfast tips

Incorporate many types of healthy foods into your breakfast, Leah Cahill advises – as this is “an easy way to ensure your meal provides adequate energy and a healthy balance of nutrients, such as protein, carbohydrates, vitamins and minerals.”

Bowl of breakfast cereal
Adding nuts and chopped fruit to cereal is “great way to start the day,” the authors say

If eating a bowl of cereal, try adding nuts and chopped fruit, or steel-cut oatmeal. This is a “great way to start the day,” Leah Cahill adds.

Senior author Eric Rimm, associate professor of medicine at the Harvard Medical School, says the team has spent decades looking at the effects of quality and composition of diet on health, and now this new study suggests overall dietary habits should also be considered in lowering risk of heart disease.

At a conference in 2012, UK scientists presented a study that explained why people who skip breakfast tend to find high calorie food more appealing later in the day: their brain circuits may be primed toward seeking it when fasting.

Comments from heart health charity

The British Heart Foundation’s senior dietitian, Victoria Taylor, has responded to the current research news on breakfast benefits. She says:

“In the morning rush it can be all too easy to skip breakfast, but this study suggests this could have a bigger impact on our health than we might think.

However, these researchers only looked at men aged over 45, so we would need to see further research to confirm that breakfast has the same impact on the heart health of other groups of people.”

Victoria Taylor adds:

“What we do know is that a healthy and filling breakfast can make that mid-morning biscuit less tempting, as well as giving you another opportunity to widen the variety of foods in your diet.

“Wholegrain toast, or cereals like porridge with low-fat milk are a good way to start the day. Try a sliced banana or dried fruit on top and you’ll be on your way to five-a-day before you’ve even left the house.” Written by

Multivitamins ‘waste of money,’ say medical experts

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“Enough is enough: stop wasting money on vitamin and mineral supplements,” say medical experts in an editorial of a leading journal that has just published three new studies examining whether routine use of vitamin and mineral supplements brings health benefits.

Writing in Annals of Internal Medicine, the editorial authors conclude that most supplements do not prevent chronic disease or death, some may even be harmful in well-nourished adults, and there is a large body of evidence to support this.

Their routine use is not justified and they should be avoided, they urge, noting that:

“This message is especially true for the general population with no clear evidence of micronutrient deficiencies, who represent most supplement users in the United States and in other countries.”

Editorial co-author Dr. Edgar Miller, professor of medicine and epidemiology at Johns Hopkins Bloomberg School of Public Health in Baltimore, MD, told CBS News that people would be better off spending money on healthy foods, such as “fruits, vegetables, nuts, beans, low-fat dairy,” and getting exercise.

US consumers spend over $28 billion a year on supplements

In the editorial, Dr. Miller and colleagues say despite “sobering evidence” of no health benefit and even of possible harm, US adults are spending more and more on multivitamins.

They note how use of multivitamins increased among US adults from 30% between 1988 and 1994 to 39% between 2003 and 2006, while overall use of dietary supplements grew from 42% to 53% over the same period.

There have been some dips – for instance, studies have linked certain supplements to negative outcomes – but overall the supplements industry has kept growing. In the US, it reached $28 billion a year in 2010. Trends in the UK and other European countries are similar, notes the editorial.

One point that stands out in the editorial is that consumers seem to react differently to evidence of negative results versus null results.

While overall use of supplements has gone up, use of certain individual supplements has gone down, for example beta-carotene and vitamin E. This decline followed reports of studies that showed these could be harmful.

On the other hand, evidence that daily supplements have null effects – that is, they make no difference to health – appear to have no effect on consumers and overall sales have kept growing.

Three studies suggest no benefit to supplements

In one of the studies published in the same issue as the editorial, Dr. Francine Grodstein, of Harvard School of Public Health, and colleagues examined data from the The Physicians’ Health Study II, to look at the effect of long-term use of multivitamins on cognitive health.

The participants were nearly 6,000 male doctors aged 65 and over, who were randomized to take either a daily multivitamin pill or placebo pill for 12 years.

Tests of memory and cognitive function showed no difference between the two groups, and the researchers conclude:

“In male physicians aged 65 years or older, long-term use of a daily multivitamin did not provide cognitive benefits.”

In another study, researchers reviewed evidence on the use of vitamin and mineral supplements to prevent heart disease and cancer, in order to update the guidelines for the US Preventive Services Task Force – an expert panel that advises the US government.

Their review found “limited evidence” to justify regular supplementation with vitamins and minerals for the prevention of cancer and cardiovascular disease (CVD).

They also note that beta-carotene appears to increase risk of lung cancer in smokers.

And in the third study, researchers looked at the role of multivitamins and minerals in preventing a further heart attack, in more than 1,700 patients recruited at least 6 weeks after a heart attack (myocardial infarction).

Having a heart attack raises a person’s risk of a further attack, stroke or death.

The patients were randomly assigned to receive either a daily high dose of multivitamins and minerals, or placebo pills for 5 years.

The study results showed no differences between the two groups in rates of chest pain, another attack, need for hospitalization, stroke or early death.

However, the authors note that these results should be treated with caution since not all participants took the pills as they should.

Strong reaction from the supplement industry

The Council for Responsibile Nutrition (CRN), a group that represents the supplement industry, has voiced strong objections to the editorial.

They argue that while it is all very well to say instead of taking supplements people should concentrate on eating a healthy diet and exercising, this “fantasy” vision fails to recognize “real life.”

Steve Mister, CRN’s President and CEO, says:

“The editorial demonstrates a close-minded, one-sided approach that attempts to dismiss even the proven benefits of vitamins and minerals. It’s a shame for consumers that the authors refuse to recognize the real-life need for vitamin and mineral supplementation, living in a fairy-tale world that makes the inaccurate assumption that we’re all eating healthy diets and getting everything we need from food alone.”

He says while not suggesting supplements are a panacea, he hopes the authors agree they have their place, especially as government studies show consumers are repeatedly failing to eat a healthy diet.

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Iron-rich foods to prevent anemia could lower dementia risk

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Researchers have discovered that low iron levels in blood and anemia could be linked to increased risks for dementia, according to a study published in the journal Neurology.

Anemia occurs when the number of red blood cells or concentrations of hemoglobin, a protein inside red blood cells, are low.

Researchers from the University of California, San Francisco and the American Academy of Neurology analyzed 2,552 adults between the ages of 70 and 79 who were participating in a Health, Aging and Body Composition study.

The study, which was carried out over an 11-year period, required the adults to participate in memory and thinking tests during this time.

At the beginning of the study, all patients were free of dementia. At the start of the research, 393 were diagnosed with anemia and 445 had developed it by the end of the study.

The results were that the patients with anemia had a higher risk of developing dementia compared with those who were not anemic. Anemia was associated with a 41% higher chance of dementia. The association persisted even after the researchers took other factors into account, such as age, sex, race and education.

Kristin Yaffe, a study author from University of California, San Francisco, says:

“There are several explanations for why anemia may be linked to dementia. For example, anemia may be a marker for poor health in general, or low oxygen levels resulting from anemia may play a role in the connection.

Reductions in oxygen to the brain have been shown to reduce memory and thinking abilities and may contribute to damage to neurons.”

Could a better diet lower the risk?

More than 3 million people in the US have anemia. Iron deficiency anemia (IDA) is the most common form. It occurs when the body does not get enough iron for healthy hemoglobin production.

Eating foods high in iron can help prevent IDA. The National Heart Lung and Blood Institute advice on anemia lists these sources as best for iron content:

Senior couple with barbecue
Will eating more iron-rich food such as red meat keep this smiling couple free of dementia?
  • Meat – especially red meat (such as beef or liver)
  • Chicken
  • Turkey
  • Pork
  • Fish
  • Shellfish.

The institute also lists the following among non-meat foods that are good sources of iron:

  • Spinach and other dark green leafy vegetables
  • Tofu
  • Peas; lentils; white, red, and baked beans; soybeans; and chickpeas
  • Dried fruits, such as prunes, raisins, and apricots
  • Prune juice
  • Iron-fortified cereals and breads.

Commenting on the study, Dr. Doug Brown of the Alzheimer’s Society, says that although this research is interesting, we shouldn’t assume that anemia is a direct cause of dementia. He says:

“Maybe our parents were right to tell us that we should eat more spinach. This interesting research suggests that lower iron levels may have a link with cognitive health later on in life.

However, more research is needed and we shouldn’t make the jump to claim that anemia causes dementia. The changes may be linked to disrupted oxygen flow to the brain or, indeed, poor health overall.”

In conclusion, Dr. Doug Brown says that “the best way to reduce your risk of dementia is to lead a healthy lifestyle.”

“Enjoy a balanced Mediterranean diet rich in fruit and vegetables, oily fish and even the occasional glass of red wine, take regular exercise and don’t smoke,” he says.

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Obesity: Not just what you eat

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Over 35 percent of American adults and 17 percent of American children are considered obese, according to the latest survey conducted by the Centers for Disease Control and Prevention. Associated with diabetes, heart disease, stroke, and even certain types of cancer, obesity places a major burden on the health care system and economy. It’s usually treated through a combination of diet, nutrition, exercise, and other techniques.


To understand how obesity develops, Prof. Amit Gefen, Dr. Natan Shaked and Ms. Naama Shoham of Tel Aviv University’s Department of Biomedical Engineering, together with Prof. Dafna Benayahu of TAU’s Department of Cell and Developmental Biology, used state-of-the-art technology to analyze the accumulation of fat in the body at the cellular level. According to their findings, nutrition is not the only factor driving obesity. The mechanics of “cellular expansion” plays a primary role in fat production, they discovered.

By exposing the mechanics of fat production at a cellular level, the researchers offer insight into the development of obesity. And with a better understanding of the process, the team is now creating a platform to develop new therapies and technologies to prevent or even reverse fat gain. The research was published this week in the Biophysical Journal.

Getting to the bottom of obesity

“Two years ago, Dafna and I were awarded a grant from the Israel Science Foundation to investigate how mechanical forces increase the fat content within fat cells. We wanted to find out why a sedentary lifestyle results in obesity, other than making time to eat more hamburgers,” said Prof. Gefen. “We found that fat cells exposed to sustained, chronic pressure — such as what happens to the buttocks when you’re sitting down — experienced accelerated growth of lipid droplets, which are molecules that carry fats.

“Contrary to muscle and bone tissue, which get mechanically weaker with disuse, fat depots in fat cells expanded when they experienced sustained loading by as much as 50%. This was a substantial discovery.”

The researchers discovered that, once it accumulated lipid droplets, the structure of a cell and its mechanics changed dramatically. Using a cutting-edge atomic force microscope and other microscopy technologies, they were able to observe the material composition of the transforming fat cell, which became stiffer as it expanded. This stiffness alters the environment of surrounding cells by physically deforming them, pushing them to change their own shape and composition.

“When they gain mass and change their composition, expanding cells deform neighboring cells, forcing them to differentiate and expand,” said Prof. Gefen. “This proves that you’re not just what you eat. You’re also what you feel — and what you’re feeling is the pressure of increased weight and the sustained loading in the tissues of the buttocks of the couch potato.”

The more you know …

“If we understand the etiology of getting fatter, of how cells in fat tissues synthesize nutritional components under a given mechanical loading environment, then we can think about different practical solutions to obesity,” Prof. Gefen says. “If you can learn to control the mechanical environment of cells, you can then determine how to modulate the fat cells to produce less fat.”

The team hopes that its observations can serve as a point of departure for further research into the changing cellular environment and different stimulations that lead to increased fat production.

Story Source:

The above story is based on materials provided by American Friends of Tel Aviv University. Note: Materials may be edited for content and length.

Journal Reference:

  1. Naama Shoham, Pinhas Girshovitz, Rona Katzengold, Natan T. Shaked, Dafna Benayahu and Amit Gefen. Adipocyte Stiffness Increases with Accumulation of Lipid Droplets. Biophysical Journal, March 2014 DOI: 10.1016/j.bpj.2014.01.045

Cite This Page:

American Friends of Tel Aviv University. “Obesity: Not just what you eat.” ScienceDaily. ScienceDaily, 20 March 2014. <>.

Role of muscle function in maintaining weight

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We all know the type: The friend or colleague who stays slim and trim without much effort and despite eating the same high-calorie fare that causes everyone else to gain weight. As it turns out, the way the muscles of the inherently thin work may give them the edge.


Daily physical activity is an inherited trait with a strong association to how fat or thin a person is. Chaitanya K. Gavini et al. previously found that aerobic capacity is a major predictor of daily physical activity level among humans and laboratory animals. In their new study, they compared female rats with high aerobic capacity (genetic tendency toward leanness) or low aerobic capacity (genetic tendency toward obesity) to investigate how muscle physiology affects leanness.

Though the rats in each group were similar in weight and lean body mass, the rats with a high aerobic capacity were consistently more active than the low capacity rats. While all the rats had similar energy expenditures when at rest, big differences in energy expenditure (calorie burn) occurred during mild exercise. The researchers found the muscles of rats with lean genes demonstrated “poor fuel economy,” meaning that they burned more calories when performing the same exercise as those with fat genes. This may be due to more lean rats having higher levels of proteins that support energy expenditure and lower levels of proteins that encourage energy conservation and/or an increased sympathetic nervous system role in powering the muscles of lean rats.

According to the researchers: “This has implications for how we consider metabolism when attempting to prevent or treat obesity. Targeting of pathways maximizing skeletal muscle energy use during physical activity may take advantage of already existing mechanisms that are endogenously employed to a greater extent in naturally lean people.”

The article “Leanness and heightened nonresting energy expenditure: role of skeletal muscle activity thermogenesis” is published in the March 2014 issue of the American Journal of Physiology — Endocrinology and Metabolism.

Story Source:

The above story is based on materials provided by American Physiological Society. Note: Materials may be edited for content and length.

Journal Reference:

  1. C. K. Gavini, S. Mukherjee, C. Shukla, S. L. Britton, L. G. Koch, H. Shi, C. M. Novak. Leanness and heightened nonresting energy expenditure: role of skeletal muscle activity thermogenesis. AJP: Endocrinology and Metabolism, 2014; 306 (6): E635 DOI: 10.1152/ajpendo.00555.2013

Cite This Page:

American Physiological Society. “Not only is she thinner than you, her muscles work better, too: Role of muscle function in maintaining weight.” ScienceDaily. ScienceDaily, 20 March 2014. <>.