Background: Human obesity is characterized by high levels of leptin, and it has been suggested that obese patients may be leptin resistant. The aim of our study was to investigate the influence of Lys656Asn polymorphism in the leptin receptor gene on metabolic response, weight loss, and serum leptin levels to a high monounsaturated fat hypocaloric diet in obese patients.
Design: A sample of 126 obese patients was analyzed in a prospective way. The hypocaloric diet had 1342 kcal, 46.6% of carbohydrates, 34.1% of lipids, and 19.2% of proteins, with a 67.5% of monounsaturated fats, during 3 months.
Results: In Lys656Lys genotype, body mass index (-1.8 ± 1.4 kg/m), weight (-4.3 ± 3.7 kg), fat mass (-3.5 ± 3.5 kg), waist circumference (-5.0 ± 2.9 cm), systolic blood pressure (-3.8 ± 10.5 mm Hg), insulin (-1.5 ± 4.6 mUI/L), and homeostasis model assessment of insulin resistance (-0.4 ± 1.9 Units) decreased. In Asn allele carriers, body mass index (1.5 ± 2.1 kg/m), weight (-3.7 ± 3.1 kg), waist circumference (-4.4 ± 3.1 cm) decreased. Only leptin levels have a significant decrease in the Lys656Lys group (-6.9 ± 10.1 ng/mL) (24.2%).
Conclusions: Patients with Asn656 allele have a different response than Lys656Lys genotype subjects, with a lack of decrease in insulin levels, leptin levels, and homeostasis model assessment of insulin resistance after weight loss.