Polymorphisms of uncoupling protein (UCP) and beta 3 adrenoreceptor genes in obese people submitted to a low calorie diet.

OBJECTIVE

To investigate whether the genetic polymorphisms of the uncoupling protein (UCP) and beta 3 adrenergic receptor (beta 3 AR) were associated with differences of weight loss in obese patients submitted to a low calorie diet.

DESIGN

Longitudinal, clinical intervention study of a 25% restriction in energy intake with respect to genotypes.

SUBJECTS

163 patients with a body mass index above 27.

MEASUREMENTS

Body weight and body mass index at baseline and after 2.5 months, genotypes by polymerase chain reaction followed by enzymatic digestion.

RESULTS

For the UCP polymorphism, two alleles, 1 and 2 were identified with respective frequencies of 0.27 and 0.73. The allele 1 was associated with lower body weight loss after diet: 4,6,5.7 and 7.1 kg for the 1-1, 1-2 and 2-2 genotypes respectively (P < 0.05). No difference in weight loss was found according to the beta 3 AR Trp64Arg mutation.

CONCLUSIONS

A genetic variant of the UCP gene is associated with a resistance to low calorie diet. This result, together with previous data on body weight gain, supports the hypothesis of a role of UCP and brown adipose tissue in the body weight regulation in humans. The importance of the Trp64Arg mutation of the beta 3 AR in the resistance to low calorie diet is still to demonstrate.