Carbohydrate craving in obese people: Suppression by treatments affecting serotoninergic transmission

We examined the existence of carbohydrate cravings, and the effects on such cravings of treatments that enhance serotonin release, among 24 obese subjects who claimed to have excessive appetites for carbohydrates. Subjects living in a college dormitory for four weeks were given three fixed meals daily and allowed to choose at will among five protein‐rich or five carbohydrate‐rich isocaloric snack foods, provided via a vending machine. For two weeks, they received no treatment (study 1) or a placebo (study 2); for the next two weeks, they received placebo, d‐1 fenfluramine or 1‐tryptophan. All but one of the subjects exhibited a marked preference for carbohydrate‐rich over protein‐rich snacks during the first two weeks of the study. The average daily intake of carbohydrate‐rich snacks was 4.1 ± 0.4 and of protein‐rich snacks 0.8 ± 0.3. Seventeen of the subjects failed to consume any protein snacks on most days during the baseline or test periods, thus it was not possible for us to examine the effect of test treatments on protein snack intake. Fenfluramine administration significantly reduced carbohydrate snacking in six of nine test subjects, as well as in the group as a whole (2.4 ± 0.6 snacks/day vs 4.2 ± 0.6 during the two‐week baseline period). Tryptophan significantly diminished carbohydrate intake in three of the eight treated subjects, and increased it in one subject; it did not significantly modify snacking patterns in the group as a whole. Placebo administration did not affect carbohydrate intake in any of the seven test subjects. These observations show that some obese people do consume carbohydrate‐rich snacks frequently and preferentially, and that this behavior can sometimes be diminished by treatments thought to enhance serotonin's release (fenfluramine) or synthesis (tryptophan)