Variability of appetite control mechanisms in response to 9 weeks of progressive overfeeding in humans.

BACKGROUND: The current epidemic of obesity demonstrates that mechanisms for maintaining human energy balance are readily subverted by adverse environmental conditions. The critical elements of this dysregulation are poorly understood. Most previous research into what regulates the intake side of the energy balance equation has been handicapped by the use of short-term within-day experimental tests. OBJECTIVE: We enrolled six non-obese men to a 17-week protocol involving three 21 days periods of progressive overfeeding (+20, +40 and +60%) separated by free diet periods to test for compensatory satiety. RESULTS: Responses to overfeeding differed markedly with evidence of 'compensators' and 'non-compensators', but on average, subsequent food intake was stimulated rather than suppressed after overfeeding in spite of markedly elevated body fat (+13%) and fasting leptin (+116%). DISCUSSION: The inefficient response of in-built appetite control mechanisms emphasizes the need to adopt intentional cognitive restraint in the modern environment when food is plentiful.