Leptin levels do not change acutely with food administration in normal or obese subjects, but are negatively correlated with pituitary-adrenal activity

BACKGROUND Leptin is a peptide secreted by white adipose tissue which has been shown to have a major influence on body weight regulation, while animal studies have revealed widespread interconnections between leptin and other endocrine systems, especially with insulin. However, its acute regulation has been little studied in the human. We have therefore investigated the effect of a 1000 kcal meal and fasting on the levels of leptin, insulin and cortisol, in both normal and obese subjects. SUBJECTS AND DESIGN We have studied the effect of food and fasting on circulating leptin levels in 20 subjects of normal body mass index (BMI range 18–25) and in a group of 12 moderately‐severely obese subjects (BMI range 34–61). We also studied the effect of food and fastina in a patient both before and after the successful removal of a pancreatic insulinoma as a model of excess insulin secretion. RESULTS Mean leptin levels were significantly higher in the obese than in the lean group (42.7 ± 3.41 vs 5.35 ± 1.55 μg/l, mean ± SEM; P