1. Plasma pancreatic polypeptide, plasma catecholamine, blood glucose, plasma insulin and plasma peptide YY concentrations were studied to assess differences between eight formerly obese and eight never-obese control women during 25 min of sham-feeding (with the sight and smell of an English breakfast) and for 5h after they had ingested the meal (3514 kJ, 50% fat, 35% carbohydrate). The post-obese women had maintained their normal body weight for at least 3 months before the study. 2. The plasma noradrenaline concentration was not different between the groups either during fasting (post-obese women 0.08±0.01 ng/ml versus control women 0.10±0.01 ng/ml) or in the significant postprandial increase (P < 0.001). The plasma adrenaline concentration increased significantly during sham-feeding in the control group from 0.024±0.004 ng/ml to 0.033±0.004 ng/ml (P = 0.02) in contrast with the post-obese women, who had significantly lower plasma concentrations of adrenaline in the fasting state (post-obese 0.016±0.003 ng/ml versus control women 0.024±0.004 ng/ml, P = 0.003), during sham-feeding (post- obese women 0.018±0.002 ng/ml versus control women 0.033±0.004 ng/ml, P=0.003) and in the postprandial increase (P=0.003). The maximal postprandial response concentrations recorded 5h after the meal were 0.025±0.003 ng/ml in post-obese women and 0.035±0.004 ng/ml in control subjects (P = 0.04). There were no significant differences in plasma pancreatic polypeptide, plasma peptide YY, plasma insulin, or blood glucose concentrations between the two groups. 3. The plasma adrenaline concentration is lower in post-obese women in the basal fasting state, during sham-feeding and in response to a meal. These results indicate that post-obese subjects respond differently to food stimulation than normal subjects.