Psychological and metabolic effects of dietary carbohydrates and dexfenfluramine during a low-energy diet in obese women

Dietary carbohydrates and dexfenfluramine (dF) have been shown to influence serotoninergic neurotransmission. To assess their effect on spontaneous physical activity, mood, sleep quality, and resting metabolic rate (RMR), 32 obese females were studied while consuming diets providing 3970 kJ (950 kcal)/d. They were randomly allocated to either a diet relatively high in carbohydrates (carbohydrate:fat:protein, 49%:22%:29% of energy intake; group 1) or to a diet relatively high in fat (carbohydrate:fat:protein, 12%:59%:29%); subjects receiving the latter diet were treated additionally with either 30 mg dF (group 2) or placebo (group 3) daily in a double-blind fashion. Spontaneous physical activity decreased in the group treated with dF compared with the other two groups (P = 0.0002). Daily self-rated questionnaires indicated that mood and tiredness were negatively affected in two groups after the first week. Subjects treated with dF lost more weight than did those in the other two groups (P = 0.013). This occurred despite a decrease in physical activity and unchanged energy intake and resting energy expenditure.