Calorie counting relies on the energy balance equation to explain body weight changes. Proponents of calorie counting claim that the change in body weight experienced by an individual is related solely to the amount of physical activity they perform, in addition to their energy intake, with a correction made for the resting metabolic rate. If we take a person of stable body weight and we increase their energy intake or decrease their physical activity, according to calorie counting ‘law’, that person will gain weight. Calorie counters claim that the key to weight loss is to create a negative energy balance by ‘dieting’ or performing increased amounts of physical activity. The main problem with calorie counting is that it oversimplifies a complex regulatory system in mammals that oversees body weight. It takes no account for example of the thermic effect of food, the thermic effect of activity, adaptive thermogenesis, appetite regulation, or behavioural modification that are under the direct control of the hypothalamus.
Many studies with good methodologies contain evidence that calorie counting cannot and does not explain changes to body weight. For example, one study1 investigated the supplementation of two groups of sugar cane workers with high and low energy supplements. The workers toiled for long hours in the fields harvesting sugar cane, and their energy intakes were considered low for the amount of work they performed. They were lean and weighed less than would be expected based on average weights for their heights. In fact the study authors calculated the energy intakes of the subjects and found that they were below the level required to maintain body weight (27 % of workers had energy intake below 80 % of the daily requirements and 45 % fell below 90 % of daily requirements). Therefore according to calorie counters, these workers should have beeen losing weight. However, the fact that their body weights were stable, despite a negative calorie balance shows the absurdity of the calorie counting hypothesis.
The authors then supplemented the diet of the workers with either a high calorie or low calorie energy drink that contained 350 kcal or 15 kcal per bottle. The supplements were distributed to the workers in the fields, and the workers were observed drinking them to assure compliance. The total energy intake was calculated to be 550 kcal per day or 24 kcal per day for 15 months, in the high and low energy groups, respectively. In the high energy drink group this caused a 10 % increase in energy intake, or 290 kcal per day. The workers were reported to enjoy the drinks and neither the workers nor the researchers knew which drink was being consumed by the subjects. At the end of the 15 months study, neither the high energy supplement nor low energy supplement groups had any changes in body weight. Measurement of the skinfold thickness at the triceps revealed that no changes in adiposity had occurred in either group (when correcting for losses in tricep thickness that occur normally as the harvest season progresses).
There results show that changes to energy intake may not result in changes to body weight. Interestingly, despite the 550 kcal per day increase in calories from the drinks, the workers on the high energy supplement only increased energy intake by 290 kcal per day, or 10 % of total calories. This the authors concluded was due to the workers eating less food at home in response to the additional calories supplied to them in the field. This illustrates the complexity of body weight regulation and shows that the hypothalamus creates behavioural and physiological changes that allow maintenance of body weight despite an increase in energy intake. One obvious answer is that the workers could work harder with the extra energy and simple oxidised in the fields. This supports other data to show that the hypothalamus is quite able to regulate body weight subconsciously through physical activity. Just as it can increase physical activity to regulate body weight down, it can also decrease physical activity to regulate body weight up.
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