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 5 h 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 5 h 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.(ABSTRACT TRUNCATED AT 250 WORDS)