Chapter 4: The Exercise Myth

Jun 26, 2019


Click here to watch a repay of the Facebook LIVE for this discussion. 

You Will Learn

  • Exercise is only a small portion of the total calories we burn in a day. 
  • The two compensations your body makes after exercise to counteract the calories you just burned. 
  • You can’t out-exercise a bad diet!


About Dr. Fung, Author of The Obesity Code and The Diabetes Code

Dr. Jason Fung is a medical doctor, nephrologist by trade, who specializes in kidney disease, type 2 diabetes, and obesity. He acknowledged that traditional medicine wastes time and resources attempting to treat symptoms of disease, rather than the cause of disease.  

You can purchase The Obesity Code book HERE. Most information in this post is direct from this book. 


Overview of the Book

Here is an outline of the book. Today I’m covering Chapter 4 in Part 2 of the book. 

  • Part 1: “The Epidemic,” explores the timeline of the obesity epidemic and the contribution of the patient’s family history. It highlights the underlying causes of obesity. 
  • Part 2: “The Calorie Deception,” reviews the current caloric theory in depth and highlights the shortcomings of the current understanding of obesity. 
  • Part 3: “A New Model of Obesity,” describes how hormones are involved in the development of obesity. These chapters explain the central role of insulin in regulating body weight and describe the vitally important role of insulin resistance. 
  • Part 4: “The Social Phenomenon of Obesity,” dives into childhood obesity and why obesity is associated with poverty. 
  • Part 5: “What’s Wrong with Our Diet?,” explores the role of fat, protein, and carbohydrates, the three macronutrients, in weight gain. In addition, it examines one of the main culprits in weight gain - fructose - and the effects of artificial sweeteners. 
  • Part 6: “The Solution,” provides guidelines for lasting treatment of obesity by addressing the hormonal imbalance of high blood insulin through proper nutrition, sleep, and stress management. 


Eat Less, Exercise More Doesn’t Work  

Last week I covered the “eat less” part of the above equation. Today I’m covering the “exercise more.”  

Historically, diet and exercise have been prescribed as treatments for obesity as if they are equally important. We assume that we can burn off the calories that we eat.  

In reality, what (and in some cases when) we eat is responsible for 95% of weight loss and weight maintenance. Exercise is responsible for 5%.  

Disclaimer: I am a Physical Therapist and LOVE to exercise and be generally active. There are many health benefits and exercise has been proven to be a key component in healthy aging and disease prevention. But when it comes to weight loss we are tremendously over-estimating its utility.  

To quote Dr. Fung on p. 54, “Exercise is like brushing your teeth. It’s good for you and should be done everyday. Just don’t expect to lose weight.”  

One analogy Dr. Fung noted was to pretend you are taking a test that is 95% math and 5% spelling. You would be silly to spend 50% of your time studying spelling as math is the majority of the material. But that is what we are doing with weight loss.  

We are spending 50% of our efforts on exercise and 50% on diet when we should really be spending 95% of our effort on nutrition and 5% on exercise.  


Increased Exercise - A Historical Perspective 

The U.S. Public Health Service began to advocate that increasing physical activity was one of the best ways to lose weight in 1966. Assuming the “eat less, exercise more” approach to weight loss was correct, we would think that as physical activity and exercise increased, more calories would be burned off, and obesity rates would fall.  

Exercise and physical activity rates have risen in all 50 states and most nations around the world. Researchers have found, however, that whether physical activity increases or decreases, it has virtually no relationship to the prevalence of obesity. Increasing exercise did not reduce obesity. It was irrelevant.  

One recent 8-country survey found that the Dutch and Italians, who exercised the least, had less than one-third the obesity rate of the Americans, who exercised the most.  

One unspoken assumption of the “eat less, exercise more” philosophy is that reduced levels of physical activity have led to the obesity epidemic. People often speak of increased time at the computer or in front of devices, or in our cars. Dr. Fung talks about research that proves exercise (and total energy expenditure) has not decreased since hunter-gatherer times but obesity has greatly increased, starting in about 1977 when our diet changed following the release of the McGovern Report.  

On page 52, Dr. Fung concludes that it is “highly improbable that decreased exercise played any role in causing obesity in the first place. If lack of exercise was not the cause of the obesity epidemic, exercise is probably not going to reverse it.” 


Reason #1: Exercise is a Small Percentage of the Total Calories We Burn 

The real term for “calories out” is total energy expenditure, or how much energy our body uses.  

Total energy expenditure = basal metabolic rate + thermogenic effect of food + non-exercise activity thermogenesis + excess post-exercise oxygen consumption + exercise. 



Basal Metabolic Rate: Housekeeping items for your body, things like breathing, maintaining body temperature, keeping the heart pumping and blood flowing, maintaining organ function, and keeping our brains active.  

Thermogenic Effect of Food: Energy used in digestion and absorption of food.  

Non-exercise Activity Thermogenesis: The energy used for everyday movement like getting in or out of bed, walking around the house, basically and ACTIVITY that is not intentional EXERCISE.  

Excess Post-Exercise Oxygen Consumption: Energy used to repair cells, replenish fuel stores, and other recovery activities after exercise.  

Exercise: Any intentional activity above and beyond day-to-day movements.  

We have wrongfully assumed that the only variable in the total energy expenditure equation is exercise, even though it is a very small part of the equation (about 10% for people who exercise). However, on page 53, Dr. Fung states that “decreased calorie intake can decrease basal metabolic rate by 40% and increased caloric intake can increase it by 50%.” 


Reason #2: Your Body Adjusts to Counteract the Calories Burned by Exercise  

  • Reducing calories in reduces calories out. Increasing calories out increases calories in. In other words, if you burn calories with exercise you will want to replace those with eating. 
  • Reducing non-exercise activity following exercise.  

Have you ever done a hard workout, gone for a walk, or just did yard work and were all of a sudden hungry afterwards? This is the first compensation your body makes. Following activity, your body increases your hunger hormones so that we eat more. This is because your body tries to maintain something called homeostasis, or a stable state.  

The second compensation your body makes is reducing non-exercise activity following a workout. If you ran 3 miles today you are going to be more likely to take the elevator, park close to the door, or skip the evening walk. You get my point.  


Reason #3: You Can’t Out-Exercise a Bad Diet 

As a general rule, you can estimate about 100 calories burned per mile of walking or running, depending on your weight. Lighter people will burn less, heavier people will burn more.  

Most adults walk at a pace of 1 mile every twenty minutes, or 3 miles per hour. If you follow the general recommendation of walking 30 minutes per day, you are walking 1.5 miles, and burning about 150 calories, plus a bit extra for the energy it takes to repair and refuel your cells.  

Often you will crave high carbohydrate food following a work-out because this provides nearly immediate energy for your body. You can replace the calories you just burned with a small apple and a tablespoon of peanut butter, or ½ cup of ice cream.  

There are not enough hours in the day to exercise off the excess and unhealthy food you eat. You can save yourself a lot of time and effort by just adopting a healthier lifestyle. 


Bottom Line 

There are 3 major factors that limit the utility of exercise when trying to lose weight:

  • Exercise is a small percentage of the total calories burned. 
  • Your body tries to replace the calories you just burned to maintain a stable state. 
  • You can’t out-exercise a bad diet.  

We need to stop thinking “eat less, exercise more” for weight loss. It will work for a little while, but eventually you will plateau, get frustrated and the weight will creep back on. We need to get to the bottom of what actually causes weight gain so we can select the best strategies to lose weight. 



1. Chapter 4. (2016). In J. Fung, The Obesity Code: Unlocking the Secrets of Weight Loss. Vancouver: Greystone Books.

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