Obesity and the parabolic nature of weight loss curve: an imposed pattern

Abstract

Introduction: The diet therapy to obesity is difficult because, following energy restriction, weight loss does not describes a linear downward curve, that is, the loss is greater on first weeks andbecame smaller late, as a parabolic curve. Objective: It was to introduce the aspects related to body weight control and propose a decomposed description of weight loss curve. Materials and methods: Review of the indexed papers searched on mainly indexingdata basis, concerning to terms: overweight, obesity, weight loss, weight control, diet, caloric restriction, energy restriction, very low caloric diet, hypothalamus, energy metabolism, energy expenditure e hormone. Results: During the energy restriction it is observed an adaptation of physiological mechanisms responsible by regulation of hunger and satiety, as a fall of leptin signaling to arcuate nucleus and increased of the parasympathetic autonomous nervous system’s tonus. This way, diet fails. In order to better describe the process, we propose a decomposition of weight loss curve in three segments and a denomination of SAR curve, because at begin of diet, the energy deficiency represents a “Shock” and there is a delay on response to this new condition. After few weeks, “Adaptation” of the mechanism responsible to maintain the energy stores occurs and continue active, becoming more efficient as a “Resistance” to additional weight loss. Conclusion: The adaptations and resistance to weight loss characterizes homeostatic control and explain, in part, the difficult found by subjects to reduce body fat.