Failure of naltrexone to affect the pleasantness or intake of food.

Two separate studies were conducted to investigate the effects of oral naltrexone on the pleasantness ratings of foods and food intake. In both studies, normal-weight, nondieting males rated hunger, fullness, mood and the pleasantness of the taste of a variety of foods before and after double-blind administration of 50 mg of naltrexone or placebo. All subjects received a test meal, in a counterbalanced, repeated measures design. In the first study, 12 subjects were given a self-selection test meal after overnight deprivation. In the second study 14 subjects were given an ice cream test meal with no deprivation. In both experiments the pleasantness of the taste of the foods, sensory-specific satiety, hunger ratings and overall energy intake were not differentially influenced by naltrexone administration. In Experiment 2, intake of the ice cream was greater after active drug administration because subjects who received active drug on the first session ate less ice cream in the placebo session. In conclusion, in the short term, naltrexone had no impact on hunger, sensory-specific satiety or food intake.