The current mainstream paradigm for weight loss centres around a strategy that causes a negative caloric energy balance. This can be achieved through dietary restriction, increased physical activity, or a combination of both. Studies confirm that energy restriction alone or in combination with exercise does result in weight loss. However, studies also confirm that much of this weight loss, as much as 50 %, may be skeletal muscle. This loss of skeletal muscle causes metabolic damage (on top of that already present) and contributes to a further deterioration of health. The metabolic changes associated with skeletal muscle loss include detrimental reductions in the resting metabolic rate and detrimental changes to hormonal homeostasis. These changes significantly increase the risk of weight regain, and this weight regain can be accounted for in most cases as 100 % adipose tissue. Cycles of calorie restriction and exercise to induce a negative energy balance therefore result in a gradual deterioration of body composition.
Evidence suggests that energy restricted diets do not cause successful long term body composition improvements. In obese subjects, evidence shows that energy restriction through diet or increased physical activity does not result in the improvements in body composition that might be expected. This is likely because weight gain is not caused by overeating, but is actually a metabolic disease caused by eating the wrong types of foods. Evidence for this viewpoint comes from studies where fat loss and body composition improvements are experienced by individuals who undertake dietary improvements, but who are not subjected to energy restriction or physical activity. Sugar is a highly obesogenic food, and in some cases, simply removing it from the diet can lead to significant fat loss with no requirement for other dietary changes.
Another of the main problems with energy restrictive weight loss strategies is the increased appetite that results from energy restriction. This creates a situation whereby it becomes inevitable that compensatory eating will occur, and this compensatory eating will in turn negate the purpose of the energy restriction. For example, one study investigated the effects of a 25 % energy deficit from diet alone or from exercise alone. The results of the study confirmed data from other studies that compensatory eating occurs when a negative energy balance is created. However, in this study, the compensatory eating was greatest in the diet group, compared to the exercise group. The authors suggests that short term and acute changes to energy balance, particularly when this restriction comes from energy intake, may result is significant and measurable compensatory eating. The driver of this increased eating behaviour may relate to the increase in palatability of induced by energy restriction.
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