It’s not simply about calories – our bodies are far more complex than that

    30 June 2015

    The first law of thermodynamics states that ‘energy cannot be created or destroyed, but can be changed from one form to another’. This is often seized upon by proponents of the ‘calories in-calories out’ theory as proof that calorie counting is the way to go, and that it therefore doesn’t what proportion of micronutrients one eats.

    But the body is shockingly complex. Thousands of simultaneous metabolic pathways are running every moment of every day in every one of the 100 billion cells that make up the human body. Energy is not only used to synthesise required molecules, repair, digest and absorb but is also lost as heat. Furthermore some reactions are more ‘exothermic’ – or heat releasing – than others. The ingestion of protein, for example, is associated with a more heat-releasing reaction than fat or carbohydrates as the body requires more energy to digest it. The measurement of energy contained in food is an inexact science and to pretend otherwise is foolish.

    Those who feel that carbohydrates are being seriously maligned at the moment and are firm believers in the old, discredited ‘fat is the enemy’ fallacy will consistently point to calories as both medium and message, treating carbs as identical to fat and protein provided the calorie content is the same. This is facetious in the extreme, and ignores all the evidence that it is refined carbohydrates, processed trans and polyunsaturated fats that are the true enemy of human health.

    The body does not react to calories; it reacts to macronutrients present in food.  A low-calorie diet works in the short term, but as research has shown, most people will regain weight. Why is this? Simple physiology. Evolutionary development has predisposed our metabolisms to decrease whenever food is scarce as a method of preservation. Resume ‘normal’ eating patterns and you gain weight, even if this gain is initially kept off by high-activity levels.

    A narrow-minded focus on calories is, essentially, pointless. 500 calories of sugar is simply not the same as 500 calories of fat. Why? Sugar stimulates the production of insulin, a hormone with a half-life of 4-6 minutes. Once insulin is present in elevated levels in response to a high carbohydrate load, the body is primed for ‘anabolism’: to build up its muscle, protein and fat stores. Blood sugar then decreases as carbohydrates are taken up by cells, and the craving for more sugar starts soon after. When this happens multiple times a day, as is the case when processed, sugary food is eaten, the path to being ‘curvy’ is initiated.

    At this point if excess fat is eaten, it will be stored as body fat. But were one to simply eat 500 calories of fat rather than sugar, the majority of the ingested fat would simply be burned for fuel in the absence of an insulin spike as without it, the body cannot store fat. This of course is a gross oversimplification. But the reality is that we eat a mixed diet, and this hormonal response is reduced. So if hormonal activity is complex, how can calories be the ‘simple’ answer? Whether or not a person gains or loses weight on a particular diet is determined by the hormonal response to that food, its micronutrients, their genetics and epigenetics, physical activity and resting metabolic rate. Calories are far from the most important consideration.

    Proper nutrition is about manipulating hormones via careful selection of healthy food, resulting in the body utilising its own fat stores as well as ingested carbohydrates, protein and fat without resulting systemic inflammation or deposition of excess fat. What constitutes ‘proper’ nutrition varies from person to person and differs based on insulin resistance, level of activity, response to certain foods and a myriad of other factors. Some individuals lose a tremendous amount of weight on a high-fat diet, others require higher levels of carbohydrates to see any effects. This is widely acknowledged by personal trainers, bodybuilders and athletes. The body is too complex for the simplistic calorie hypothesis to be definitive. Numerous researchers in the field attest to this and for those wanting a primer on the latest calorie research, I would suggest the work of Dr. Jonathan Baylor.

    I sincerely hope that my gross oversimplification of human biochemistry has illustrated my fundamental point: that you cannot ignore the complexity of the reality in favour of an over-simplistic concept to explain complex phenomena.

    Those bleating about ‘calories in, calories out’ as the solution to obesity really need to start reading, and understanding the literature that has been available for the last 20 years rather than simply repeating what others have told them.  As a Professor of Orthopaedic surgery so elegantly observed during my medical school days: ‘You have to learn to tell the difference between chicken salad and chicken s*&t.’