The appetite-modulating hormone ghrelin transmits changes in food intake to the central nervous system. In patients with anorexia nervosa, weight gain reduces elevated fasting ghrelin levels to normal, however, less is known about the effects on postprandial ghrelin levels. In 20 female anorectic in-patients (25.6 +/- 1.0 years; body mass index (BMI) 15.1 +/- 0.3 kg/m2) a standardized test with 250 ml fluid meal (250 kcal: 9.4 g protein, 34.4 g carbohydrates, and 8.3 g fat) was performed at three different times (at admission, after partial weight gain of at least 2 kg, and at discharge) and compared to healthy controls (n = 6; BMI 21.1 +/- 0.7 kg/m2). Plasma ghrelin levels were measured preprandially as well as 20 and 60 min postprandially by a commercially available radioimmunoassay (Phoenix Pharmaceuticals, USA). At admission plasma ghrelin levels significantly decreased postprandially (from 871.9 +/- 124 to 620.3 +/- 80 pg/ml 60 min after meal; P < 0.005). After partial weight gain (2.8 +/- 0.1 kg; BMI 16.1 +/- 0.3 kg/m2) postprandial ghrelin concentrations decreased from 597.0 +/- 79 to 414.7 +/- 39 pg/ml (P < 0.0001), at discharge (weight gain: 7.6 +/- 0.5 kg; BMI 17.9 +/- 0.4 kg/m2) from 570.4 +/- 78 to 395.4 +/- 44 pg/ml (P < 0.0001). Mean postprandial ghrelin decrease was not significantly different between the three tests (29, 25, and 26%, respectively) or to controls (20%). In anorectic patients mean postprandial ghrelin decrease did not change during weight gain. These findings indicate that in anorexia nervosa the suppression of ghrelin release by acute changes of energy balance (feeding) is not disturbed and that it is independent from chronic changes in energy balance (weight gain).