Abstract

Intranasal oxytocin produces anorectic effects on snack intake in men when tested in the absence of deprivation-induced hunger, but its effects on food intake in women without eating disorders have not been reported. Oxytocin may reduce food intake by reducing stress eating, since it inhibits ACTH release. The present study adopted a double-blind, repeated measures and fully concealed crossover protocol in which 38 women self-administered 24 IU of oxytocin or placebo intranasally, ate lunch, and underwent two consecutive stress tests. Snack intake was assessed 15-20 minutes after lunch, via a sham taste test. Salivary cortisol was measured throughout the test period every 15 minutes. Oxytocin significantly reduced sweet fatty snack intake independently of any effect on salivary cortisol, which declined over time at a similar rate after either drug or placebo. Ratings of sweet taste were slightly reduced by oxytocin, but only in self-reported stress eaters. These results differ from previous studies with men that found an effect of oxytocin on postprandial cortisol levels. However, previous research assayed the less active form of plasma cortisol and did not control for protein intake, which can drive elevated cortisol. The finding that oxytocin reduces snack intake in females after acute stress has important implications for appetite regulation and its treatment in obese people and in those with eating disorders.