Sex differences in HPA axis activity in response to a meal

BACKGROUND:Sex may influence the relationship between HPA axis functioning and obesity. This has been suggested to be due to sex-specific differences in body composition, body fat distribution and psychological variables. Age and the use of oral contraceptives may also influence the relationship between HPA axis functioning and obesity. OBJECTIVE:To systematically investigate whether body composition, body fat distribution, psychological variables, age, or possible oral contraceptive use contribute to sex differences in HPA axis activity in response to a meal. METHODS:Subjects were men (n=19) and women (n=19) between 18 and 51 years old with BMI between 20.3 and 33.2 kg/m(2). HPA axis activity was measured by salivary free cortisol levels before consuming a meal, and at 45, 75 and 125 min postprandial on four repeated test days. Anthropometric and body composition measurements were performed. Questionnaires were used to assess cognitive eating behavior and trait anxiety level. RESULTS:No differences between the test days in postprandial cortisol responses appeared. Responses were significantly higher in men compared with women (p<.05). No significant correlations were found between cortisol concentrations and sex-specific body composition or body fat distribution. Psychological variables did not contribute to differences in cortisol responses after a meal between men and women. In women, baseline cortisol concentrations correlated inversely with age (p=.024). CONCLUSION:Higher HPA axis activity following a meal in men vs. women remained irrespective of sex-specific differences in body composition, body fat distribution, psychological variables, or in age. In women baseline cortisol concentrations were age-dependent.