[Effects of excessive isocaloric intake of either carbohydrate or fat on body composition, fat mass, de novo lipogenesis and energy expenditure in normal young men].

Ten pairs of normal young men were overfed by 5 MJ per day for 21 days with either a carbohydrate-rich or a fat-rich diet (C- and F-group). The two subjects of a pair were requested to follow each other throughout the day to ensure similar physical activity. The increase in body weight and fat mass were not significantly different between the C- and the F-group. Heat production during sleep did not change during overfeeding. The accumulated faecal loss of energy, dry matter, carbohydrate and protein was significantly higher in the C- than in the F-group. Hepatic de novo lipogenesis was 212 g per 21 days in the C-group and was too low to be determined in the F-group. Whole body de novo lipogenesis was positive in six of the ten subjects in the C-group (mean: 332 g per 21 days). It is concluded that the increase in body weight and fat mass during overfeeding of isocaloric amounts of diets rich in carbohydrate or in fat was not significantly different, and that surplus of carbohydrate seemed to be converted to fat both by hepatic and extrahepatic de novo lipogenesis.