Background: Peripheral administration of glucagon-like peptide-1 (GLP-1) for four hours, to normal weight and obese humans, decreases food intake and suppresses appetite.
Objective: The aim of this study was to assess the effect of an eight hour infusion of GLP-1 on appetite and energy intake at lunch and dinner in obese subjects.
Design: Randomised, blinded cross-over design with intravenous infusion of GLP-1 (0.75 pmol x kg(-1) min(-1)) or saline.
Subjects: Eight obese (body mass index, BMI, 45.5 +/- 2.3 kg/m2) male subjects.
Measurements: Ad libitum energy intake at lunch (12.00 h) and dinner (16.00 h) after an energy fixed breakfast (2.4 MJ) at 08.00 h. Appetite sensations using visual analogue scales, (VAS) immediately before and after meals and hourly in-between. Blood samples for the analysis of glucose, insulin, C-peptide, GLP-1 and peptide YY. Gastric emptying after breakfast and lunch using a paracetamol absorption technique.
Results: Hunger ratings were significantly lower with GLP-1 infusion. The summed ad libitum energy intake at lunch and dinner was reduced by 1.7 +/- 0.5 MJ (21 +/- 6%) by GLP-1 infusion (P = 0.01). Gastric emptying was delayed by GLP-1 infusion, and plasma glucose concentrations decreased (baseline: 6.6 +/- 0.35 mmol/L; nadir: 5.3 +/- 0.15 mmol/L). No nausea was recorded during GLP-1 infusion.
Conclusions: Our results demonstrate that GLP-1 decreases feelings of hunger and reduces energy intake in obese humans. One possible mechanism for this finding might be an increased satiety primarily mediated by gastric vagal afferent signals.