The effects of two different hypocaloric diets on glucagon-like peptide 1 in obese adults, relation with insulin response after weight loss

Objective: Few studies have investigated the effect of type of diets on GLP-1 concentrations. The aim of this study was to compare the effect of two diets on circulating GLP-1 levels and the relation with insulin response after weight loss. Methods: A population of 118 obese patients were analyzed. Patients were randomly allocated to two groups: (a) Diet I (low carbohydrate) and (b) Diet II (low fat). Biochemical and anthropometric parameters were measured before and after 3 months of hypocaloric diet. Results: Fifty-two patients (12 male/40 female) were treated with Diet I and 66 patients (21 male/45 female) with Diet II, In Group I, basal GLP-1 levels did not change after dietary treatment (9.4 +/- 3.3 vs. 9.9 +/- 3.1 ng/ml; ns). In Group II, GLP-1 levels decreased significantly (8.4%) (9.2 +/- 3.3 vs 8.7 +/- 3.1 ng/ml; P <.05). In the multivariate analysis with a dependent variable (levels of GLP-1), only insulin levels remained as an independent predictor in the model (F=5.9; P <.05), with an increase of 0.6 ng/ml (95% Cl 0.1-1.1) GLP-1 concentrations with each increase of 1 mUl/ml of insulin. Conclusion: A hypocaloric diet with a low fat percentage decreased GLP-1 levels with a direct correlation with insulin levels. Nevertheless, patients with a hypocaloric diet with a low carbohydrate percentage treatment did not change GLP-1 levels. Diet macronutrient manipulation on GLP-1 response could be useful in an obesity nutrition therapy. (C) 2009 Elsevier Inc. All rights reserved.