Social and public health issues in adaptation to low energy intakes

The centrality of the concept of energy requirement for a number of major national policy areas as well as the large proportion of Third World population believed to be exposed to energy stress and therefore needing to adapt emphasize the importance of the adaptation issue. This paper reviews the evidence of adaptation to low energy intakes in real-life conditions and, while identifying the reduction in physical activity as potentially the most powerful energy-sparing strategy, shows that the currently available evidence does not support the recourse to this behavioral strategy in developing countries undergoing recurrent seasonal energy stresses. Distinction is made between behavioral adaptation mechanisms, which include only actions taken after weight loss and directly resulting in immediate reduction of energy intake, and those actions that are taken in anticipation of a forth-coming energy stress and do not necessarily reduce energy expenditure.