Why Calorie In – Calorie Out Does Not Equal Body Fat

I read a book a couple of weeks ago that I think has a lot of potential in terms of changing our perception of why and how we gain or lose weight. The book is by Dr. Jason Fung and the title is “The Obesity Code”.

She's ready to give it her all!

As we all know, we are getting more overweight and obese despite all the diet advice we are bombarded with on a daily basis. Eat less, move more, eat less fat, eat less sugar, eat less red meat, eat more vegetables, eat more protein, eat more fibre, eat less wheat, eat more complex carbohydrates. The list goes on and on. And if you are like me who has struggled with her weight and has been on more diets than I can count, you know that the whole calorie in – calorie out thing is just not that simple. I’ve had phases of meticulously writing down what I ate and how many calories I consumed and how many calories I burned doing exercise. Unfortunately, a 3500 calorie deficit a week did not result in one pound of weight loss. Not for me anyway. If it did, I’d probably be zero kilos now. Dr. Fung calls this the calorie deception.

The book is over 270 pages with full bibliography, i.e. all the statements are backed by reference to studies and the latest research. I’m nerdy like that, I’m not easily convinced unless there is scientific evidence for any hypothesis.

I’m not going to summarize the whole book here. I will only focus on Dr. Fung’s arguments on why the calorie in – calorie out concept doesn’t help for weight loss. 

We have been told by doctors, government agencies, dietitians, fitness experts, fitness enthusiasts, countless “influencers” on social media and many more that our weight is a result of how many calories we consume and how many we burn. You consume more calories than you burn, you gain weight. You consume less calories than you burn, you lose weight. So either you eat less, or you move more, or you do both. Everyone tells you that. I’ve been telling people that. I myself have more or less successfully been trying to lose weight like this for two decades. Counting calories, doing exercise. So why do I get stuck on a certain weight? Why do people lose weight and then put it back on?

We are very quick to blame a lack of discipline. If someone is obese, we think it is their own fault. We assume that they are gluttons or have fallen off the diet wagon. Every time I stop losing weight, I try to be stricter with my eating, or exercise more, or even both. I’m sure most people know this cycle. You start a diet, do exercise, you lose weight, all is great. And then it creeps back up and you even gain a couple of extra pounds. So you blame yourself and your lack of discipline and start again on your diet. And you feel deprived, hungry, tired, cold…. Well, many of us anyway.

According to Dr. Fung, one problem with this calorie in – calorie out concept is that it seems so simple, whereas it is actually based on several false assumptions. These are as follows:

  1. Calories in and Calories out are Independent of Each Other

This is wrong. Dr. Fung highlights research that shows that these two variables are dependent on each other. If you decrease the calories in, you trigger a reduction in calories out. Studies show that the resting metabolic rate slows with a reduction in calories. So strength decreases, heart rates slow down, heart stroke volume goes down, body temperature drops, physical endurance drops, blood pressure drops, you lose hair, your nails go brittle. As a result of the metabolic slowdown you lose very little weight.

2. Basal Metabolic Rate is Stable

When we think about the calories out part of the equation, we only ever think of exercise. But measuring calorie expenditure is very difficult compared to calorie consumption. So we assume that calorie expenditure remains constant, except for exercise. However, total energy expenditure includes basal metabolic rate, thermogenic effect of food, nonexercise activity thermogenesis, EPOC (excess post-exercise oxygen consumption) AND exercise. “The total energy expenditure can go up or down by as much as 50 per cent depending upon the caloric intake as well as other factors” (p. 30).

3. We Exert Conscious Control Over Calories In

We are quick to blame the lack of willpower when we eat. However, there are several hormonal systems in our body that tell us when to eat and when to stop. We stop eating when the satiety hormones kick in. For example, you get up in the morning and you smell bacon and eggs. That may make you hungry. However, if you have just eaten a big breakfast, then the same smell probably makes you slightly sick. The smell is the same, but your reaction to it is hormonal.

4. Fat Stores Are Essentially Unregulated

Every system in the body is regulated by hormones: growth, blood sugars, sexual maturation, body temperature and the list goes on and on. However, when it comes to fat growth, we are told that it is simply due to eating too much. This has already been proven to be wrong. Leptin is probably the most well known hormone to regulate fat growth, but there are many more. As a result, fat growth is a “…hormonal, not a caloric disorder.” (p. 31)

5. A calorie is a calorie

This is probably my biggest problem with all the diet advice out there. Because, yes, of course, a calorie is a calorie. We all know the First Law of Thermodynamics: Energy can neither be created nor destroyed in an isolated system. However, we cannot consciously regulate how the body uses the energy that comes in. It could be used for heat production, protein production, increased heart rate, detoxification of kidney or liver, digestion, breathing, fat production etc. So we all would love if the energy was used for protein production, but we don’t want it to be deposited as fat.

100 calories are a 100 calories. But are 100 calories of butter really the same as 100 calories of sugar candy? The question really is, are all calories equally likely to make you gain fat? Of course not. The sugar will spike your blood sugar and therefore provoke an insulin response. The butter will not significantly increase blood sugar nor insulin.

So, Dr. Fung argues that the above 5 assumptions have all been proven wrong and that as a result, a caloric reduction is not the primary factor in weight loss.

I hope you find this as interesting as I do. For 50 years or so we’ve been told to eat less and move more, but we only ever get more obese, sick and unhappy because we think we lack willpower and discipline. Dr. Fung changes the approach totally by saying that obesity is a hormonal disorder. And by addressing the hormones (or imbalances thereof) you can lose weight, even reverse diabetes type 2. 

What are your thoughts on this? If you like to know more about his book, let me know.

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