Exercise is not Total Energy Expenditure

Exercise is often (wrongly) assumed to be extremely important for weight loss. Watching popular shows such as ‘The Big Loser’ often portray exercise as the most important factor in weight loss. Courageous Drs. Malhotra, Noakes and Phinney recently pointed this out in a recent editorial.  The reason for this commonly made error lies in the misunderstanding of Total Energy Expenditure or ‘Calories Out’. Consider the following:

Fat gained = Calories In – Calories Out

This is sometimes called the First Law of Thermodynamics. It’s funny how nutritionists always reference thermodynamics, drawn to as children to amusement parks, but physicists who spend decades studying thermodynamics never, never, never talk about calories. Like the smelly annoying kid with no friends, calorie-enthusiants want to pretend that nutrition, too, is a ‘hard science’ like physics with ‘inviolable’ laws. Sad, and more than a little pathetic. Any who…

In this equation – we can easily measure “Fat Gained” and “Calories In” The main focus, then should be on the ‘Calories Out’ part of the equation, not the ‘Calories In’. This is what exercise enthusiasts have always preached. However, what is the ‘Calories Out’ portion of the equation?

The amount of calories used in a day (Calories Out) is more accurately termed total energy expenditure (TEE) – the sum of basal metabolic rate (BMR), thermogenic effect of food (TEF), non-exercise activity thermogenesis (NEAT), excess post-exercise oxygen consumption (EPOC) and, of course, exercise.

TEE = BMR + TEF + NEAT + EPOC + Exercise

The key point here is that TEE is not the same as exercise. The overwhelming majority of TEE is not exercise but the BMR: metabolic housekeeping tasks such as breathing, maintaining body temperature, keeping the heart pumping, maintaining the vital organs, brain function, liver function, kidney function, etc.

Let’s take an example. BMR for a lightly active average male is roughly 2500 calories per day. Walking at a moderate pace (two miles per hour) for forty-five minutes every day, would burn roughly 104 calories. In other words, that will not even consume 5 percent of the TEE. The vast majority (95 percent) of calories are used for basal metabolism.

What is typically done is to assume that BMR, TEF, NEAT and EPOC are all constant over time, and therefore we only have to worry about exercise. This is absolutely false. BMR depends on many factors, including

  • genetics,
  • gender (BMR is generally higher in men),
  • age (BMR generally drops with age),
  • weight (BMR generally increases with muscle mass),
  • height (BMR generally increases with height),
  • diet (overfeeding or underfeeding),
  • body temperature,
  • external temperature (heating or cooling the body) and
  • organ function.

NEAT is the energy used in activity other than sleeping, eating or exercise; for instance, in walking, gardening, cooking, cleaning and shopping. TEF is the energy used in digestion and absorption of food energy. Certain foods, such as dietary fat, are easily absorbed and take very little energy to metabolize. Proteins are harder to process and use more energy. TEF varies according to meal size, meal frequency and macronutrient composition. Excess post-exercise oxygen consumption (EPOC—also called after-burn) is the energy used in cellular repair, replenishment of fuel stores and other recovery activities after exercise.

Because of the complexity of measuring BMR, NEAT, TEF, and EPOC, we make a simple but erroneous assumption that these factors are all constant over time. This assumption leads to the crucially flawed conclusion that exercise is the only variable in TEE. Thus, increasing Calories Out becomes equated with Exercise More. One major problem is that the BMR does not stay stable. Decreased caloric intake can decrease BMR by up to 40 percent. Increased caloric intake can increase it by 50 percent.

What determines the energy output of the system? Suppose we consume 2,000 calories of chemical energy (food) in one day. What is the metabolic fate of those 2,000 calories? Possibilities for their use include

  • heat production,
  • new protein production,
  • new bone production,
  • new muscle production,
  • cognition (brain),
  • increased heart rate (heart),
  • increased stroke volume (heart),
  • exercise/physical exertion,
  • detoxification (liver),
  • detoxification (kidney),
  • digestion (pancreas and bowels),
  • breathing (lungs),
  • excretion (intestines and colon) and
  • fat production.

We certainly don’t mind if energy is burned as heat or used to build new protein, but we do mind if it is deposited as fat. There are an almost infinite number of ways that the body can dissipate excess energy instead of storing it as body fat.

So now our equation looks like this

Fat gained = Calories In – BMR – NEAT – TEF – EPOC – Exercise

All of these are highly variable depending upon genetics, gender, age, weight, height, diet, body temperature, external temperature, cognition, new bone/protein/muscle synthesis, and organ function. Do you still think cutting a few ‘Calories In’ a day will work? Do you really think increasing Exercise, which is only 5% of the game will make a difference?

Not likely. Diet and exercise are important, but they are not equally important like macaroni and cheese. Diet is Luke Skywalker and Exercise is an Ewok. Consider a baseball analogy. Bunting is an important part of the game, but perhaps only 5% of it. Should we spend all our energy and practice time on the bunt? Obviously not. Putting too much emphasis on bunting hurts us because it does not leave time to practice more important parts of the game – pitching, hitting and fielding.

Exercise is the same. Sure, it’s important for a number of very good reasons. But we can’t expect it to produce significant weight loss. It’s a minor player. Emphasizing exercise detracts from the real issue of dietary problems.

Compensation: The hidden culprit

The fact that exercise never produces as much weight loss as we think has actually been well known in research for several decades, at the minimum. Why does actual weight loss fall so far below projected? The culprit is a phenomenon known as “compensation”—and there are two major mechanisms.

First, caloric intake increases in response to exercise—we just eat more following a vigorous workout. (They don’t call it “working up an appetite” for nothing.) A prospective cohort study of 538 students from the Harvard School of Public Health found that “although physical activity is thought of as an energy deficit activity, our estimates do not support this hypothesis.” For every extra hour of exercise, the kids ate an extra 292 calories. Caloric intake and expenditure are intimately related: increasing one will cause an increase in the other. This is the biological principle of homeostasis. The body tries to maintain a stable state. Reducing Calories In reduces Calories Out. Increasing Calories Out increases Calories In.

The second mechanism of compensation relates to a reduction in non-exercise activity (NEAT). If you exert yourself all day, you are less likely to exercise in your free time. The Hadza, who were walking all day, reduced their physical activity when they could. In contrast, those North Americans who were sitting all day probably increased their activity when given the chance.

This principle also holds true in children. Students aged seven and eight years who received physical education in schools were compared to those who did not.16 The physical education group received an average of 9.2 hours per week of exercise through school, while the other group got none.

Total physical activity, measured with accelerometers, showed that there is no difference in total activity over the week between the two groups. Why? The PhysEd group compensated by doing less at home. The non-PhysEd group compensated by doing more when they got home. In the end, it was a wash.

In addition, the benefit of exercise has a natural upper limit. You cannot make up for dietary indiscretions by increasing exercise. You can’t outrun a poor diet. Furthermore, more exercise is not always better. Exercise represents a stress on the body. Small amounts are beneficial, but excessive amounts are detrimental.17

Exercise, is simply not all that effective in the treatment of obesity—and the implications are enormous. Vast sums of money are spent to promote physical education in school, the Let’s Move initiative, improved access to sports facilities, and improved playgrounds for children—all based on the flawed notion that exercise is instrumental in the fight against obesity.

If we want to reduce obesity, we need to focus on what makes us obese. If we spend all our money, research, time and mental energy focused on exercise, we will have no resources left with which to actually fight obesity. This is NOT to say that exercise is not healthy for you. It is like brushing your teeth.  Good for you, do it every day, but don’t expect to lose weight.

We are writing a final examination called Obesity 101. Diet accounts for 95 percent of the grade, and exercise for only 5 percent. Yet we spend 50 percent of our time and energy studying exercise. It is no wonder that our current grade is F—for Fat.

See The Exercise Myth – Part I

2017-10-28T21:27:53+00:0034 Comments

About the Author:

Dr. Fung is a Toronto based kidney specialist, having graduated from the University of Toronto and finishing his medical specialty at the University of California, Los Angeles in 2001. He is the author of the bestsellers ‘The Obesity Code’ and ‘The Complete Guide to Fasting’. He has pioneered the use of therapeutic fasting for weight loss and type 2 diabetes reversal in his IDM clinic.

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webgrrrrl
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webgrrrrl

I find this discussion very interesting. Before I embarked on a keto diet of 85% fat, I tried the traditional low-fat diet and exercise plan. The weight loss consultant/nutritionist I hired was very frank that I should expect to go to 3 50-minute spinning classes 7 days a week in order to burn 1200 calories a day. At the same time, the diet she gave me was a low-fat diet of 800 calories a day. This is the traditional advice given to women by professional nutritionists, in my experience and what my friends tell me they have been advised as… Read more »

John
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John

I do agree. I don’t see where a 200 calorie walk would do a thing…other than bore you to death. While I don’t think exercise alone can achieve FAT loss (not weight loss), I do think that someone running or walking five miles per day and engaging in some sort of strength training is going to lose a much higher percentage of bodyfat and less muscle mass than someone who is sedentary. To me, not exercising while dieting, leads to one becoming “skinny fat”. I am curious if how fasting affects muscle mass if one exercises vs no exercise.

Christoph Dollis
Guest

“I do agree. I don’t see where a 200 calorie walk would do a thing…other than bore you to death.”

With all due respect, I think you’re wrong. If you do that 200 calorie walk after eating [LINK], that’s 150 calories or so of glucose that isn’t going to make it into your blood vessels, which results in lower hbA1C, less advanced glycation end-products (the main cause of diabetic complications), and lower natural or supplemental serum insulin—therefore less growth factors for cancer, less blood-vessel plaque (the main cause of death for diabetics), and less insulin resistance.

John
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John

Perhaps..in a tiny way. It’s a slow, non productive walk. Won’t do a thing to encourage muscle mass retention, won’t raise your heart rate, won’t tax your cardiovascular system and will do very little to prevent glucose from entering your blood vessels, though proper diet will. Your link talks about one hour of aerobic activity. A 200 calorie walk is hardly aerobic.

Christoph Dollis
Guest

Hi John,

Just because one hour of exercise was done in this study, doesn’t mean this is the only protocol that is beneficial.

I found this talk, Goodbye Diabetes, interesting. The doctor stresses the value of post-meal exercise, but not necessarily an hour per session!

Martin Levac
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Martin Levac

Carbs eaten _have_ to go through blood vessels. Everything else you said is true. But, only when comparing walking vs not walking. When comparing eating carbs vs not eating carbs, it’s no longer true. Not eating carbs in the first place is better in all those things you listed. Therefore not eating carbs gives you a genuine choice of walking for pleasure or to go somewhere, instead of walking to compensate in part for the poison you just ate. Also, since you didn’t eat that poison, the walk you’re taking is that much easier to do, cuz you know, you… Read more »

Miss Dior
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Miss Dior

Gee John, thanks for sneering at my preferred form of exercise.

Exercise doesn’t directly help you lose weight. Everyone is missing the point. Exercise helps with insulin resistance. That’s the underlying problem.

Walking is helping to reduce my insulin resistance. Read more, sneer less.

Hildegard
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Hildegard

I’m a long walk lover too. The stress-reduction that happens on a long walk with my dog are far more important than whether or not it burns enough calories, raises my heart rate, or improves muscle tone.

Kathy from Maine
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Kathy from Maine

Like you, I have been told by doctor after doctor that if you’re a woman over 50, you must accept the fact that you have to exercise at high-intensity for 60 from 5 to 6 days a week just in order to MAINTAIN your weight. Talk about wanting to simply give up. How’s that even possible with most people’s schedules? “But it’s your health we’re talking about here.” Yeah, no way to respond to that.

Miss Dior
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Miss Dior

Your doctor is a pill. Walking is a good way to exercise but the most important way to tackle the underlying problem – insulin resistance – is to fast. Have you had your blood sugars checked?

Bernard P.
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Bernard P.

So this post would be Number V in the Exercise series?

Monica
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Monica

Hello All the community here 😉 Being a person who likes excercise and run just for my own pleasure, I can testify that doing a lot of excercise will certainly have no significan efect on fat loss not even weight loss, on the contrary weight tends to go up as you gain muscle. I have never been overweight nor fat but, had some belly fat that I tried like crazy to get rid of by several types of rutines and results were poor not so say cero. I tried so hard that got tired of and stop but, curiosly now… Read more »

Onlooker from Troy
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Onlooker from Troy

Jason,

Thanks for the link to the article, “Debunking the Hunter-Gatherer Workout”, as I had a link to the study but this article by one of the study authors is much better to share with people.

The only regrettable part of it is the end when he states that we have to reduce the number of calories we eat to lose weight. Ugh (though he does specifically put the finger on sugar, the worst offender). He should have limited his message to that which he knows!

Wendy
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Wendy

When I go low carb and try to exercise along with it, my weight loss stops so I just stop exercising and poof, kicks in again. Yes, possibly water fluctuations and also too low calorie. Maybe my body just hates cardio?

Christoph Dollis
Guest

For those interested in an extremely time-efficient and safe formal exercise program that will increase fitness enough so that it becomes easier to embark on other activities, you might want to consider high-intensity strength training done under control, mostly on machines for additional safety, as little as 12 minutes per week (although I do it for 50-60 minutes per week, counting some less intense exercises): http://www.bodybyscience.net/home.html/?page_id=18 More: http://paleodiabetic.com/2012/01/30/is-your-strength-training-regimen-outdated/ The author, Doug McGuff, MD, advises basically low-carb or Paleo nutrition. I’m more of a fan of micronutrient-dense plant-based food, but essentially I follow his exercise protocol with a few extra exercises… Read more »

Christoph Dollis
Guest

From the first link above about the book Body by Science, which is mainly about time-efficient exercise, but also has a nutrition component: “Part Five: Nutrition “In this section we examine what a healthy diet for humans truly consists of and also go into some depth on the role of insulin in the big picture of human health [emphasis added].” I own this book. Dr. McGuff’s and Dr. Fung’s views about insulin’s problematic role in causing diabetes are similar and they share a similar nutrition philosophy as well (although McGuff’s passion is high-intensity strength training going back to his boyhood).… Read more »

John
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John

I worked with Ken Hutchins (Super Slow) as my trainer for a few years doing the Super Slow protocol. While It was a productive workout, neither it nor a brief, intense workout is something that the majority of people can or are willing to do. I love them, used to do personal training for Nautilus (when Art Jones owned it) and still do two brief, highly intense workouts per week.
I found that most clients would not put forth the significant mental and physical effort to achieve optimum benefit.

John
Guest
John

Arthur Jones wrote extensively about HIT in the early 70s. The concept is not anything new and Jones based the designs of his machines on HIT. Later, his son, Gary improved on the Nautilus equipment with Hammer Strength equipment. Arthur’s last foray into equipment was with MedX, which is the most bio mechanically and productive equipment made today. McDuff and Hutchins utilized this equipment in developing the Super Slow protocol.

Christoph Dollis
Guest

True, it isn’t new. And most people wouldn’t put in the effort to make it a true bodybuilding workout. But by pushing oneself as hard as one is willing for a brief period of time once or twice a week, once will gain many benefits including making other activity easier.

That’s been my experience, and I’m no bodybuilder.

Thanks for offering your experience!

Drew Baye
Guest

Doug McGuff helped popularize the SuperSlow protocol and has made contributions to how it is taught, but Ken Hutchins and Brenda Hutchins developed the protocol (based on suggestions by Nautilus studio owner Vince Bochichio) during the Nautilus-funded Osteoporosis study at the University of Florida during the early 1980’s.

Christoph Dollis
Guest

What about postprandial exercise’s effect on lowering blood glucose without requiring (endogenous or exogenous) insulin for this purpose?

In other words, total energy expenditure may stay the same, but by purposely timing a significant quantity of exercise as postprandial, even if only chores, blood glucose is lowered, and insulin also is lowered. This has to be metabolically beneficial.

I would say there is a strong argument that timing matters, and that can only be done with some thought to intentional exercise.

Christoph Dollis
Guest

Here’s another study that takes into consideration the compensation effect, but also shows the value of exercise. Exercising, on purpose, twice a week may lead to more net energy expenditure, exercising four times a week leads to a bit more net energy expenditure, and exercising six times per week leads to less energy expenditure. The problem may not have been the formal exercise, which is probably good; the problem was more likely trying to do over 9 hours of formal exercise per week. However, we shouldn’t throw the baby out with the bath water and drop formal exercise. Intentionally getting… Read more »

Christoph Dollis
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Simon Thompson
Guest
Simon Thompson

It is a litmus test for determining the cluelessness of any Authority. Any mention of “Moderation” and “Exercise” in the same sentence, and I know I am reading zombie vomit.

John
Guest
John

What a ridiculous statement. Some people are physically capable of doing balls to the walls, no holds barred exercise sessions and achieve great results in doing so. Others, due to age or physical limitations cannot and must adhere to light or moderate exercise regimen.
Exercise programs need to be geared toward individuals..not to someone’s “one size fits all” idea of fitness.
Perhaps, you can back up your comment with credentials and evidence to back it up.

Christoph Dollis
Guest

I agree, John, and there is also variety of intensity in exercise to train different aspects of fitness.

John C
Guest
John C

I started with a personal trainer six years ago when I weighed 215 pounds. I also walked a lot and worked in my garden. My stiffness and muscle and joint pains were eliminated but after three years I had gained ten pounds. I believe that this was due to the compensation that Dr Fung describes. Then I started a calorie-restricted, low-fat diet and lost 60 pounds. Looking back it was also a relatively low-carb diet too, because reducing total calories also reduced calories from carbohydrates but I didn’t understand that at the time. I knew I couldn’t sustain the low-fat… Read more »

Jerome Benthamite
Guest

As Prof; Ben Goldacre says in Bad Pharma: The devil Is in the details”. What ones measure makes all the difference. I don’t recommend exercise to those with significant weight issue as a way to improve the end results over the period of the next year. However, for those who are so inclined and enjoy the activity, going to a gym, and having the support of a friend or physical trainer, this activity will improve the motivation to stay on a diet. But most don’t enjoy doing this. Think of adults like children, make it pleasant and they will do… Read more »

Samuel
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Samuel

I am a retired engineer and I have done plenty of time with thermodynamics over my career, but it never even occurred to me to wrap a control volume around the human body and apply the 1st law as a basis for weight loss. Taking this approach basically represents an abuse of thermodynamics in the same sense that statistics can be regularly abused and misapplied. In support of your analysis, I am an avid biker and I train over the summer. I do not ride in the winter. Regular 50-60 mile rides are standard for me in the summer, and… Read more »

michael
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michael

Dr. Fung, I have gone back and read your blog from the beginning and I find it fascinating and convincing. However, I felt the same way when I read “Why We Get Fat”. Yet, as you showed in your earlier posts, every weight loss study I have ever seen shows the familiar U curve with initial weight loss followed by regain starting at around 6 months. Of course, there are many anecdotal stories of people with successful weight loss using various diets. But, the actual studies do not support long term weight loss for even small populations. I keep hoping… Read more »

kfacwpup
Guest

Unfortunately, there are no trials to point to. Only common sense. Fasting has a history stretching back (at least) 2000 years of success.

michael
Guest
michael

Unfortunately, science has a long history of debunking common sense.

Betty
Guest
Betty

I have eaten an extremely low-fat diet my entire life, and have restricted my calories countless times starting in childhood (I am now middle-aged) in an attempt to control my weight. I also am the coldest person I know — I wear long underwear and sweaters on days when my coworkers wear light shirts. And still I freeze. I know a lot of this may be my age, gender, and genetics, but I am wondering now if it is not also due to my lifelong diet. (By the way, I also have super-dry skin, and because of these two things,… Read more »

OSAMA AFIF
Guest
OSAMA AFIF

In line 30 is this example of 2500 calorie TEE or BMR?

“BMR for a lightly active average male is roughly 2500 calories per day. “