^*Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Department of Human Biology, Maastricht University, Maastricht, The Netherlands

Correspondence: M.S. Westerterp-Plantenga, Department of Human Biology, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands. E-mail: m.westerterp@hb.unimaas.nl

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Received 26 April 2004; Accepted 3 February 2005.

Abstract

Objective: Postprandial glucagon-like peptide 1 (GLP-1) release seems to be attenuated in obese subjects. Results on whether weight loss improves GLP-1 release are contradictory. The aim of this study was to further investigate the effect of weight loss on basal and postprandial GLP-1 release in overweight/obese subjects.

Research Methods and Procedures: Thirty-two overweight/obese subjects participated in a repeated measurement design before (BMI, 30.3 2.8 kg/m²; waist circumference, 92.6 7.8 cm; hip circumference, 111.1 7.4 cm) and after a weight loss period of 6 weeks (BMI, 28.2 2.7 kg/m²; waist circumference, 85.5 8.5 cm; hip circumference, 102.1 9.2 cm). During weight loss, subjects received a very-low-calorie diet (Optifast) to replace three meals per day. Subjects came to the laboratory fasted, and after a baseline blood sample, received a standard breakfast (1.9 MJ). Postprandially, blood samples were taken every one-half hour relative to intake for 120 minutes to determine GLP-1, insulin, glucose, and free fatty acids from plasma. Appetite ratings were obtained with visual analog scales.

Results: After weight loss, postprandial GLP-1 concentrations at 30 and 60 minutes were significantly lower than before weight loss (p < 0.05). Glucose concentrations were also lower, and free fatty acids were higher compared with before weight loss. Ratings of satiety were increased, and hunger scores were decreased after weight loss (p < 0.05).

Discussion: In overweight/obese subjects, GLP-1 concentrations after weight loss were decreased compared with before weight loss, and nutrient-related stimulation was abolished. This might be a response to a proceeding negative energy balance. Satiety and GLP-1 seem to be unrelated in the long term.