One day of food restriction does not result in an increase in subsequent daily food intake in humans

The purpose of this study was to examine the effect of one day of food restriction on subsequent spontaneous daily food intake and the recovery of body weight in humans. Twenty-two, non-restrained females were fed from Monday to Friday for four weeks using food prepared and measured in the Cornell Metabolic Laboratory. For the first week, all participants ate ad libitum. For each subsequent Monday, participants were divided into three groups in which either they (a) ate ad libitum, (b) were restricted to eating 1200 kcal (5040 kj), or (c) were fasted. From Tuesday until Friday participants ate ad libitum. During each session, all food consumed as well as body weight were measured. Body weight did not change following the day of ad libitum eating, but decreased significantly after the day of food restriction decreasing still further after fasting, indicating high compliance with study protocol. Although the loss in body weight was regained within four days, the recovery was accomplished without any increase in spontaneous food intake. Although no direct measurement of energy expenditure was made in this study, the results strongly suggest that decreases in metabolic rate play a more dominant role in the recovery of body weight following food restriction than the control of food intake.