Proceedings of the Nutrition Society

Oskar Kellner Symposium 2011 organised by the Leibniz Institute for Farm Animal Biology jointly with the Nutrition Society, Hotel Neptun, Warnemünde, Germany.9–11 September 2011,

Symposium on ‘Metabolic flexibility in animal and human nutrition’

Session II: Metabolic flexibility and regulation

How dieting makes some fatter: from a perspective of human body composition autoregulation

Abdul G. Dullooa1 c1, Jean Jacqueta1 and Jean-Pierre Montania1

a1 Department of Medicine/Physiology, University of Fribourg, Chemin du musée 5, CH-1700 Fribourg, Switzerland

Abstract

Dieting makes you fat – the title of a book published in 1983 – embodies the notion that dieting to control body weight predisposes the individual to acquire even more body fat. While this notion is controversial, its debate underscores the large gap that exists in our understanding of basic physiological laws that govern the regulation of human body composition. A striking example is the key role attributed to adipokines as feedback signals between adipose tissue depletion and compensatory increases in food intake. Yet, the relative importance of fat depletion per se as a determinant of post-dieting hyperphagia is unknown. On the other hand, the question of whether the depletion of lean tissues can provide feedback signals on the hunger–appetite drive is rarely invoked, despite evidence that food intake during growth is dominated by the impetus for lean tissue deposition, amidst proposals for the existence of protein–static mechanisms for the regulation of growth and maintenance of lean body mass. In fact, a feedback loop between fat depletion and food intake cannot explain why human subjects recovering from starvation continue to overeat well after body fat has been restored to pre-starvation values, thereby contributing to ‘fat overshooting’. In addressing the plausibility and mechanistic basis by which dieting may predispose to increased fatness, this paper integrates the results derived from re-analysis of classic longitudinal studies of human starvation and refeeding. These suggest that feedback signals from both fat and lean tissues contribute to recovering body weight through effects on energy intake and thermogenesis, and that a faster rate of fat recovery relative to lean tissue recovery is a central outcome of body composition autoregulation that drives fat overshooting. A main implication of these findings is that the risk of becoming fatter in response to dieting is greater in lean than in obese individuals.

(Online publication April 05 2012)

Correspondence

c1 Corresponding author: Dr. Abdul G. Dulloo, fax +41 26 300 9734, email abdul.dulloo@unifr.ch