Modalities of the food intake-reducing effect of sibutramine in humans

Sibutramine is a serotonin and noradrenaline reuptake inhibitor exerting a weight reducing effect partly via its anorectic properties. We investigated the effects of 15 mg sibutramine on objective (intake) and subjective (sensations) parameters of eating behavior in 24 young male subjects. At 0830 h subjects took either placebo or sibutramine in a counterbalanced order, followed by a fixed amount of breakfast. Intake was covertly recorded in the laboratory until the dinner meal, and then until the next morning using diary reports. Sibutramine induced a highly significant reduction in energy (1304 kJ, p < 0.001), protein (294 kJ, p < 0.001), fat (414 kJ, p < 0.01), and carbohydrate (CHO, 594 kJ, p < 0.001) intakes compared to placebo. This reduction was further enhanced when 24-h intake was analyzed (1601 kJ, p < 0.001). The effect of sibutramine occurred mainly at lunch (637 kJ, p = 0.005). Throughout the test day the number of items consumed and the weight of food were reduced by sibutramine (1.6, p < 0.01 and 222 g, p < 0.001, respectively), whereas energy density was not changed. Meals minus dessert items were the most altered by sibutramine. A specific CHO reduction was found in the dinner meal, although the proportions of macronutrients in total daily energy intake were not changed by sibutramine. Hunger ratings began to be lower than placebo 240 min after sibutramine. These results show that a single dose of sibutramine in lean humans induces a potent reduction in intake, and that its action is modulated according to the time of occurrence and the structure of the meal.