Effect of naltrexone on food intake, hunger, and satiety in obese men.

Increasing doses of naltrexone (25 to 200 mg) given over 4 consecutive days reduced intake of laboratory luncheon meals by 30% in 17 obese men. Meal size remained suppressed in the laboratory during the week following naltrexone administration. Water intake in the laboratory and body weight were not affected. Rates of ingestion and subjective ratings suggested that naltrexone reduced appetite rather than promoted early satiation. Nausea and other side effects occurred on 1 or 2 days during the naltrexone week in seven subjects whose food intake was reduced. Food intake was also reduced in seven of the remaining 10 subjects who reported no adverse reactions. These results suggest that a conditioned taste aversion or a conditioned anorexia may have developed in some subjects.