Influence of Trp64Arg Polymorphism of Beta 3-Adrenoreceptor Gene on Insulin Resistance, Adipocytokines and Weight Loss Secondary to Two Hypocaloric Diets

Abstract

Objective: To investigate the influence of the Trp64Arg polymorphism in the beta 3-adrenoreceptor gene on adipocytokines, insulin resistance and weight loss secondary to a low fat versus a low carbohydrate diet. Methods: A population of 193 obese patients was analyzed. A nutritional evaluation was performed at the beginning and at the end of a 2-month period in which subjects received 1 of 2 hypocaloric diets. Results: 172 (89.1%; 44 males, 128 females) subjects had the genotype Trp64/Trp64 (wild-type group) and 21 subjects (10.9%; 4 males, 17 females) had Trp64/Arg64 (mutant-type group). In the wild-type group BMI, weight, fat mass, waist circumference, systolic blood pressure, glucose, triglycerides, insulin, homeostasis model assessment (HOMA) and leptin decreased significantly regardless of the diet. In the mutant-type group, this was the case for BMI, weight, waist circumference, fat mass and leptin levels. Only leptin levels have a significant decrease in the wild-type group (diet I 13.7%, diet II 26.3%, p < 0.05 for both). In the mutant group, leptin decreased as well (diet I 22.5%, diet II 30.1%, p < 0.05 for both). Conclusion: The metabolic effect of mild weight reduction by 2 hypocaloric diets is greatest in subjects homozygous for the normal beta 3-adrenoreceptor gene. Improvement in glucose, insulin and HOMA is better than in the mutant-type group.