The objective of our study was to investigate the relationship between hypothalamus/pituitary/adrenal (HPA) axis functioning and dietary restraint in normal weight (BMI between 20 and 25 kg/m(2)) men and women. We therefore assessed in 38 men and 38 women HPA axis functioning, through measuring 5-hour cortisol exposure and cortisol feedback functioning through a dexamethasone (4 mg) suppression test. Eating behavior was assessed through the Three Factor Eating Questionnaire and body composition through hydro densitometry and deuterium dilution method. No relationship between HPA axis functioning and dietary restraint was found in men. Normal weight women with a restraint score >/=9 showed increased cortisol concentrations over a 5-hour time period, increased cortisol concentrations after a dexamethasone (4 mg) suppression test, higher BMI, and higher body fat percentage, when compared to women with a restraint score <9. Moreover, a positive relationship was found between cortisol concentrations over a 5-hour time period and dietary restraint in combination with the disinhibition score (R(2)=0.23, p<0.001). We conclude that in normal weight women hyperactivity of the HPA-axis is related to dietary restraint especially in combination with disinhibition. AD - Department of Human Biology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.