One of the biggest myths of the nutrition and diet industry is the calorie myth. Dietitians and nutritionists all over the world still repeat this tired old mantra that if you shed a certain number of calories from your diet, you will lose weight. Unfortunately even in the ” low carb” community calorie counting is still being practiced whereby various apps are used to calculate calorie requirements according to height, weight and desired weight loss and a calorie deficit is set accordingly. Macro nutrient intake is then calculated in percentages of each according to the calorie calculation.
This is wrong and if you are still basing your weight loss program or macro nutrient calculations on calories, chances are good, you are going to be frustrated by the lack of long term results.
So what is a “calorie”? A Calorie is a measure of the amount of energy required to heat one kilogram of water one degree Celsius. It was first used in engineering and physics, but eventually found its niche in nutrition, where it is used to measure the amount of energy food contains.We determine the number of “calories” in a food by, quite literally, burning it and measuring how much heat it generates.How does this relate to food? Well, the human body requires energy in order to operate. Everything from brain activity to blood flow requires energy so it has been assumed that we can measure this energy in the form of calories. Our bodies simply don’t work this way , they are not mechanical engines. They do not burn the food we eat in a fire and convert the heat into mechanical work.
A little math
We have all been told that 3500 calories equals a pound of fat or 454grams. So if we reduce our calorie intake by 500 calories a day, we should lose a pound a week, or 454grams. Where does this calculation come from?
Human fat contains 87% lipid (fat) this is widely accepted but also an estimate. 87% of 454 is 395 – so that would be 395grams of pure fat. Fat has 9 calories per gram. So we multiply 395 grams by 9 (calories) we arrive at 3555 calories per pound of fat. (206,207)
It looks like a very simple concept and as Fred Stare, founder and former chair of the Harvard University Nutrition Department said “Calories are all alike, whether they come from beef or bourbon, from sugar or starch, or from cheese and crackers. Too many calories are just too many calories”. Or are they?
A calorie is just a unit of energy until it enters the human body and when you take a moment to contemplate that human beings are biologically complicated and different types of food influence different chemical reactions within the body, it becomes absurd that an energy unit like a calorie alone can determine the make-up of your body.
Different calorie sources can have very different effects on hormones, energy expenditure and the brain regions that control hunger and food intake. All the possible fates of an ingested “calorie”literally make up a biochemistry text book.
To emphasise this point let’s take a look at just 2 examples protein and fructose.
Proteins are made up of chains of amino acids. Some proteins, such as meat, are readily digested and absorbed. Some are poorly digestible, such as those found in grains like wheat and corn, and part of them will either feed gut bacteria or be excreted. Once protein is absorbed, its composition of amino acids determines how much of the protein we can use to build and repair and how much must be burned for energy or excreted.
Once we have absorbed enough complete protein for our body’s needs, additional protein will still be converted to glucose, burned for energy, or excreted.
We can clearly see that a “calorie” of meat protein that is digested, absorbed, and used to build or repair our bodies is not equal to a “calorie” of meat protein surplus to our needs. Nor is it equal to a “calorie” of wheat protein that is only partially digested, poorly absorbed, and disruptive to the digestive tract itself.
How about fructose then ?
Fructose is sent to the liver, where it is converted into glycogen and stored for future use. However, fructose has many other possible fates, all bad. It can fail to be absorbed, resulting in it feeding gut bacteria in the intestine resulting in SIBO ( small intestine bacterial overgrowth) which may significantly interfere with digestion of food and absorption of nutrients, primarily by damaging the cells lining the small bowel. If our liver is already full of glycogen, fructose is converted to fat contributing to NAFLD ( non alcoholic fatty liver disease) and visceral obesity. And when our liver is overloaded, fructose can remain in circulation, where it can react with proteins or fats to form AGEs (advanced glycation endproducts), useless pro-inflammatory molecules.
Even different fats have different fates ! The fate of dietary linoleic acid differs from the the fate of DHA, the fate of palmitic acid, or the fate of butyrate, and their effects on our nutritional and metabolic state will also differ.
Depending on WHAT you eat different amounts of energy is available to the body.Protein and Carbohydrate contain 4 calories per gram and fat contains 9 calories per gram. Protein, carbohydrate and fat are converted to energy in the body in different ways. This conversion itself uses up energy. Carbohydrates are easily converted by the body, using up only 6-8% of their calories in this process. Fat uses 2-3% but protein uses 25 -30% of its consumed calories to convert protein foods into amino acids. You can see that in somebody who eats a high carbohydrate diet there will be more calories available to the body than in someone who eats a high protein diet. Simply put 100 calories of protein end up as 75 calories and 100 calories from carbohydrate end up as 94 calories.
How can anybody come to the realistic conclusion that a calorie is a calorie ?
I can already hear some argue that we still need to count calories of ” good foods” but here is where you really need to listen up.
Decreased energy in will decrease energy out !
A major problem the calorie in calorie out theory is that the two do not work independently of each other.
When we decrease calories in, the body decreases calorie out. Feed your body less and your body uses less energy. If you keep cutting your calorie intake, your metabolic rate decreases. In order to lose more weight, you then need to decrease your calorie intake further. This makes sense. It’s logical that the body would try to preserve itself. In times that food is scarce the body is not going to keep burning up energy at the same pace as when food is abundant. We can compare this is earning money. Say you earn $5000 a month. Once you pay your living expenses you still have $1000 to blow on eating out and a few luxuries. Then you get retrenched. Your income has dried up. Are you going to continue to spend $1000 a month on luxuries ? NO of course not.You are going to do what you can to reduce your expenses !
This is why all conventional diets ultimately fail. We are told to eat less, move more. The less we eat the slower our metabolic rate becomes. Our weight loss plateaus and we reduce out consumption further until we have reduced our metabolism to the point of feeling cold, tired and sick. We then give up the diet because we feel dreadful and we are no longer losing weight and what happens ? We pick up weight faster than we lost it because our metabolic rate has not recovered from our deprivation diet. Don’t think that you can make up for the decrease in metabolism by increasing exercise.Studies have shown that even a massive increase in amounts of exercise it is simply not enough to overcome the drastic slowdown in metabolism. An excellent explanation of this in this video lecture by Dr Jason Fung
Dr Jason Fung’s blog post Insulin Causes Weight Gain – Hormonal Obesity IV gives far more insight into the causes of obesity and the solutions for it. For those who want to understand this subject better I recommend you pop onto his website.
Watch his video lectures on The Aetiology of Obesity here
“For decades we believed the Caloric Reduction as Primary (CRaP) hypothesis of obesity that turned out to be as useful as a half-built bridge. Study after study showed that reducing calories did NOT lead to weight loss. Patient after patient tried to lose weight by restricting calories with consistent failure. But we couldn’t abandon the calorie model so what was left to do? Blame the patient, of course!
But, of course, the problem was the CRaP hypothesis. It was just wrong. Increased calories did not cause obesity so reducing calories didn’t cause weight loss. Exercise didn’t work either, as we will see in a future series. So, what was the real aetiology of obesity? Insulin.” Dr Jason Fung
Calorie counting becomes a fixation in many. Spending hours trying to calculate energy in /energy out, obsessing over exact portions of food, trying to calculate how much energy has been expended during exercise so they can balance the amount in with the amount out, is a habit that becomes hard to break. Dedicated calorie counters regularly deny themselves certain foods and often make less healthy food choices or avoid social situations involving food in an attempt to eliminate calories from their diet. Calorie counting is stressful and not conducive to learning to eat to appetite as we should. When you stop eating once you’ve reached an artificial calorie limit (rather than when you feel satisfied), you lose your sense of hunger and satiety, which can perpetuate fears of food and trigger binge eating
Of course just because calorie counting is not an accurate way to determine how much food we need and we do not encourage it, does not mean that we now have an open invitation to eat through the fridge contents every day. We need to use a bit of common sense. For some guidance on how to eat correctly on a low carb diet read this How much food should I eat ? .