Hyperphagia and weight loss during fluoxetine treatment

To report the unusual coincidence of weight loss with increased appetite and food intake in a patient treated for depression on two separate occasions with fluoxetine.

A 27-year-old woman experienced a modest weight loss during treatment for depression with fluoxetine. The weight loss was associated with a reported increase in daily caloric intake and consumption of a greater proportion of dietary fat than usual for the patient. The same patient was treated again with fluoxetine more than a year later and again experienced weight loss associated with an increase in appetite, caloric intake, and dietary fat consumption.

Fluoxetine is a selective serotonin reuptake inhibitor that often is associated with a modest weight loss when used for the treatment of depression, although it also has been reported to have the opposite effects of weight gain and hyperphagia in some patients. The effects on weight usually are assumed to be the result of primary effects on appetite, but the discrepancy between the appetite and weight changes in this case challenges the applicability of that assumption in all cases.

The effects of fluoxetine on appetite and weight may be mediated by partially distinct mechanisms and might conceivably involve a direct metabolic effect in some patients.