Genetic variation in the beta 3-adrenoreceptor gene (Trp64Arg polymorphism) and its influence on anthropometric parameters and insulin resistance under a high monounsaturated versus a high polyunsaturated fat hypocaloric diet.

OBJECTIVE

The aim of our study was to investigate the role of Trp64Arg polymorphism of the beta 3-adrenergic receptor (beta 3-AR) gene on metabolic changes and weight loss secondary to a high monounsaturated fat versus a high polyunsaturated fat hypocaloric diet in obese subjects.

MATERIAL AND METHODS

A population of 260 obese subjects was analyzed. In the basal visit, patients were randomly allocated for 3 months to either diet M (high monounsaturated fat hypocaloric diet) or diet P (high polyunsaturated fat hypocaloric diet).

RESULTS

There were no significant differences between the positive effects (on weight, body mass index, waist circumference, fat mass) in either genotype group with both diets. With diet P and in genotype Trp64Trp, glucose levels (-6.7 ± 12.1 vs. -1.2 ± 2.2 mg/dl; p < 0.05), total cholesterol (-11.2 ± 8.1 vs. -1.0 ± 7.1 mg/dl; p < 0.05), low-density lipoprotein (LDL) cholesterol (-9.7 ± 10.1 vs. -2.2 ± 8.1 mg/dl; p < 0.05), triglycerides (-11.7 ± 13.1 vs. +1.7 ± 10.3 mg/dl; p < 0.05), homeostasis model assessment for insulin resistance (HOMA-R; -0.7 ± 1.1 vs. -0.3 ± 2.1 units; p < 0.05) and insulin levels (-1.8 ± 4.6 vs. -1.0 ± 9.1 mIU/l; p < 0.05) decreased.

CONCLUSION

The metabolic effect of weight reduction by the two hypocaloric diets is greatest in subjects with the normal homozygous beta 3-AR gene. Improvements in total cholesterol, LDL cholesterol, triglyceride, glucose, insulin and HOMA-R levels were better than in the heterozygous group.