Obesity: The allostatic load of weight loss dieting

The obesity epidemic that is prevailing in most countries of the world is generally attributed to the increased amount of opportunities to be in positive energy balance in a context of modernity. This obviously refers not only to sedentariness and unhealthy eating that may dominate life habits of many individuals but also to unsuspected non-caloric factors which produce discrete allostatic changes in the body. In this paper, the focus is put on the impact of some of these factors with the preoccupation to document the allostatic burden of weight loss. Thus, beyond the fact that modernity favors opportunities to eat much and not to be active, the proposed conceptual integration leads to the conclusion that a modern lifestyle makes weight loss more difficult for obese individuals. In addition to the natural effects of weight loss favoring resistance to lose fat, a lifestyle promoting shorter sleep duration and more cognitive demand produces allostatic changes that may interfere with weight loss. The case of persistent organic pollutants (POPs) is also discussed as an example of the potential detrimental effects of a contaminated environment on metabolic processes involved in the control of energy expenditure. Taken together, these observations suggest that weight loss is more than ever a search for compromise between its metabolic benefits and its allostatic effects promoting body weight regain. (C) 2011 Elsevier Inc. All rights reserved.