The effect of the 5-HT re-uptake inhibitor fluoxetine on food intake and body weight in healthy male subjects.

Eleven healthy male subjects of normal body weight received either 60 mg of the 5-HT re-uptake inhibitor fluoxetine (FXT) or matching placebo daily for two weeks, with a minimum one month wash-out period between treatments. Subjects attended on days 1, 8 and 15 from 08.50 h to 15.15 h in each treatment period when food and fluid intake, body weight, pulse and blood pressure, pupil diameter and plasma levels of FXT and NorFXT were measured and visual analogue scales (VAS) for subjective ratings of hunger, satiety, thirst, mood, arousal, nausea and gastric discomfort were completed. The trial was of a double-blind randomised crossover design, each subject acting as his own control. FXT reduced food intake by 15.7 per cent on day 1; by 12.6 per cent on day 8 but not on day 15. Hunger ratings were lowered by FXT on days 8 and 15 but not on day 1. Subjects were less thirsty when taking FXT but there was no concomitant reduction in fluid intake. FXT produced some mydriasis and slowed heart rate. In two weeks treatment with FXT there was a statistically significant weight loss of 1.07 kg compared to a mean weight gain of 0.15 kg on placebo. The incidence of reported side effects was low, drowsiness and stomach discomfort were reported by some subjects on days 8 and 15.