Preferences and cravings for sweet high-fat foods observed among obese and bulimic patients may involve the endogenous opioid peptide system. The opioid antagonist naloxone, opioid agonist butorphanol, and saline placebo were administered by intravenous infusion to 14 female binge eaters and 12 normal-weight controls. Eight of the binge eaters were obese. During infusion, the subjects tasted 20 sugar/fat mixtures and were allowed to select and consume snack foods of varying sugar and fat content. Naloxone reduced taste preferences relative to baseline in both binge eaters and controls. Total caloric intake from snacks was significantly reduced by naloxone in binge eaters but not in controls. This reduction was most pronounced for sweet high-fat foods such as cookies or chololate. No consistent effects on taste preferences or food intakes were observed with butorphanol. Endogenous opioid peptides may be involved in mediating taste responses and preferences for palatable foods, notably those rich in sugar and fat.
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compared the effects of opioid antagonists across diets (3,47) found that naloxone and naltrexone caused greater reductions in the intake of palatable cafeteria diets as compared to laboratory chow. Other studies addressed the effects of opioid peptides on the consumption of two palatable dietary ingredients: sugar and fat. Naloxone suppressed stress-induced sucrose hyperphagia (8,55) and selectively reduced intakes of carbohydrate and fat in a dietary self-selection paradigm (49). Conversely, the agonists morphine (50) and butorphanol (64) selectively increased fat consumption. Some investigators have proposed that the primary role of the opioid peptide system is in mediating overeating that is associated with exposure to palatable (47) or high-fat foods (64). Opioid peptides may thus influence energy intakes by mediating the pleasure response to foods (42). Sensory preferences for sweet taste, in particular, appear to be under opioid control. It may be that opioid blockade renders palatable foods less rewarding (15,63). In studies with rats, opioid antagonists were most effective in reducing intakes of palatable sweet liquids such as glucose, sucrose or saccharin solutions (36, 41, 45, 54). Conversely, morphine enhanced preferences for sweet taste (12) and stimulated the intake of sweet solutions. Central administration of mu and delta receptor agonists also increased intakes of 1Supported by U.S. Public Health Service Grants DA05471, DK38073 and CRC Grant 5MOIRR00042. 2Requests for reprints should be addressed to Adam Drewnowski, Human Nutrition Program, School of Public Health M-5170, University of Michigan, Ann Arbor,/vii 48109-2029.
- Binge eating
- Endogenous opioid peptides
- Food consumption
- Taste response