PHYSIOLOGICAL ADAPTATIONS TO SLIMMING
The loss of body fat can lead to a range of physiological outcomes which, in turn, affect the further loss of body fat. Physiological adaptation to weight and fat loss can be divided into predictable changes (such as the decline in RMR in response to the loss of lean mass) and adaptive changes (where the body actively works to reduce the rate of weight loss). Dr Rudy Leibel and his colleagues from Rockefeller University in New York have tried to quantify the adaptive changes in lean and obese people as they lose weight. For a 10 per cent weight loss, they found that total energy expenditure declined by about 450kcal, of which about half could be explained by the changes in body composition and half could be considered adaptive.
Studies at Cambridge University on a particular species of desert mouse for example, have shown that when compared with a ‘dry mouse—or one accustomed to plenty of food—the desert mouse is able to adapt to decreases in body weight caused by lack of sustenance by simply slowing down its metabolic processes. Humans have less facility to actively alter metabolic processes to match changes in food intake, although adaptations do certainly occur.
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