CARBOHYDRATE BALANCE AND THE REGULATION OF DAY-TO-DAY FOOD-INTAKE IN HUMANS

The hypothesis that carbohydrate stores are an important determinant o f voluntary food intake was tested by covert dietary manipulation of c arbohydrate stores in nine men during 2d of continuous whole-body calo rimetry that provided half-hourly monitoring of energy and fuel balanc e. On day 1 subjects were fed diets intended to maintain energy balanc e but containing carbohydrate at either 3% (depletion) or 47% (control ) energy. Average carbohydrate balance changed by 153 +/- 42 g (xBAR /- SD). Subsequent (day 2) ad libitum food intake from a normal diet o f fixed macronutrient composition was identical on the control and dep letion protocols: 12.73 +/- 2.24 and 12.72 +/- 2.01 MJ, respectively. The carbohydrate-depletion protocol caused a suppression of carbohydra te oxidation (174 +/- 41 vs 256 +/- 39 g, P < 0.001) and a reciprocal elevation in fat oxidation (120 +/- 11 vs 89 +/- 12 g, P < 0.001). The se readjustments in fuel utilization were the primary mechanism for re -establishing carbohydrate balance. This study does not support the hy pothesis that the need to maintain specific carbohydrate stores is a d eterminant of food intake in the short term.