Th e consumption of excess calories as carbohydrates (CHO)-rich, protein-poor snacks characterizes the overeating of obese CHO cravers, premenstrual women, patients with Seasonal Affective Disorder, and former smokers. This specific appetite for CHOs may involve m-ain serotonin, as the synthesis and release of this neurotransmitter can increase following consumption of CHG-rich foods. To examine whether weight loss produced by serotoninergic drugs involves a selective reduction in CHO intake, obese females who consumed at least 30% of their daily calories from CRO-rich snacks were treated with dexfenfluramine ({DFJ 15 mg b.i. Seven FL subjects, 2 PL subjects, and 1 DF subject withdrew from the study due to side effects; other withdrawals were due to intercurrent illness or personal problems. Prior to treatment, subjects consumed over 40% of their daily CRO intake from snacks. Both of the drugs selectively decreased CRO snack intake (p < 0.05); DF, but not FL, also decreased meal CRO intake (p < .025). These results suggest that weight loss following treatment with serotoninergic drugs may relate to a selective decrease in CRO appetite. [Neuropsychopharmacology 9:201-210, 1993] brain neurotransrnission by blocking brain serotonin reuptake; OF through its metabolite, nordexfenflura mine, also releases serotonin into synapses.It has been suggested that the weight loss produced by these drugs may be related to their effect in spe ciftcally decreasing the excessive intake of CHO-rich foods (Wurtman et al. 1985;Ferguson and Feighner 1987). Because such foods are usually rich in fat, reduc ing CHO intake can account for a substantial reduction in total calorie intake (Wurtman et al. 1985;Ferguson and Feighner 1987).