When dieting, it’s not all about calories

Many people are of the opinion that when dieting for weight loss, it is all about counting calories. If you want to lose weight, you just eat fewer calories or do extra exercise to burn more calories. That’s it, just one of those two options. But that isn’t true.

The idea is, all diets are just a means of getting people to eat fewer calories. If you follow a vegan diet and lose weight, then that’s just because cutting out animal products caused you to eat fewer calories. It doesn’t matter that you just ate vegetables, it just matters that you got less total energy from food.

The idea would be the same if you switched to a keto diet and lost weight–the diet must have worked because you ate fewer calories. Not because you didn’t eat sugar, not because you were in a state of ketosis.

The concept is derived from the assumption that the body can be imagined as a simple energy-burning machine, where any extra energy you eat must be stored as fat. You burn some average amount of calories every day from exercise and basic metabolism. Likewise, if you don’t eat as many calories as you burn, it is assumed that those missing calories from your diet will be made up for by your body burning its own fat. Then it’s assumed that you can just determine how many calories you burn in a day, and then extra calories eaten above that number must lead to fat gain and eating fewer calories than that number leads to body fat loss. That’s it, no other details to worry about. This would work the same way regardless of what one is eating.

This concept holds some appeal because it borrows the language of energy-balancing from physics and appears to be rooted in common sense. However, this fails to consider how the body actually processes energy, which is complex and involves a wide variety of chemical pathways. The body doesn’t just burn the food in a pure oxygen environment, as food companies do to assess the food’s total energy content. In fact, the calories in some foods many not even be fully absorbed by the digestive system. And this also doesn’t consider how food consumption can impact hormones, which can also affect whether body fat is stored or broken down.

There are a lot of factors at play beyond just counting calories. This is particularly clear when you consider the research on short-term fasting, where one might skip breakfast or eat all of their meals within a fixed time window such as eight hours. Consider a recent randomized, controlled trial which demonstrated quite conclusively that when it comes to obesity and health, generally there are dietary factors other than simple caloric intake.

This study in question compared groups of mice that were fed a very unhealthy diet. One group of mice were allowed to eat at any time. The other group were only allowed to eat during an eight-hour window. The total amount of food provided was the same, and both groups ended up eating the same number of calories every day.

So, if counting calories was the only important factor in a diet, you’d expect the two groups of mice to end up about the same healthwise, right? That’s not what happened. At the end of the experiment, the mice that were allowed to eat whenever they wanted were hugely overweight, had unhealthy livers, and the equivalent of type 2 diabetes in humans. That’s what normally happens to mice with this particularly unhealthy diet. But the interesting part is that the group of mice who could only eat during an eight-hour window were perfectly healthy. They were normal weight and had no applicable health problems. The mice looked hugely different.

These results show us quite clearly that diet isn’t just about counting calories.  Even though they ate the same number of calories, one group of mice was quite obese and the other group maintained a healthy weight.  Now, this is an animal study, so the results can’t be directly applied to humans–it merely points the way for further research.  But on the positive side of an animal study, animals don’t lie about how much they ate, how much alcohol they drank, or how many cigarettes they smoked on their surveys. So you really do know with a much higher degree of certainty what those mice ate and how much of it, so the results are all the more convincing.

This is very good news. Caloric restriction isn’t a very good tool for weight loss, so we should be glad that it’s not the only one available.  That’s why so few people have success losing (and keeping off) weight with very popular caloric-restricted diets. If this is surprising, consider the Women’s Health Initiative, the most ambitious, important weight-loss study ever undertaken. This enormous randomized trial involving almost 50,000 women evaluated a low-fat, low-calorie approach to weight-loss. They were persuaded to reduce daily caloric intake by 342 calories and increase exercise by 10 percent. Researcher projected a weight loss of 32 pounds over a single year based on their understanding of thermodynamics. When the final results were tallied in 2006, the experiment proved the opposite of conventional thinking. Despite good compliance, over seven years of calorie-counting led to virtually no weight loss–not even a single pound. Therefore, something we now know is the endocrine system must have superseded the overly simplified thermodynamic arithmetic associated with the concept of caloric restriction.

If your main goals are to lose weight, don’t simply jump to calorie restriction. If you want long-lasting results, you need to better understand your body.


Dr. John Jaquish, who wrote this article, is a research professor at Rushmore University and the inventor of X3, a bone density-building medical device used by professional athletes and Olympians and professional bodybuilders.