[Body weight- independent variations in HDL-cholesterol following gastric bypass]

Bariatric surgery has multiple beneficial effects on lipid profile in patients with morbid obesity. However, these changes can be attenuated by weight regain. This retrospective study was designed to assess the effects of gastric bypass(GBP) on different lipid fractions over a 6 year follow-up.

We studied 177 patients (135 women)with morbid obesity (BMI 44.2+0.4 kg/m2) aged 42.4+0.9 years before and 3, 6, 9, 12, 24, 36, 48, 60 and 72 months after laparoscopic proximal GBP. Anthropometry, body composition measurement (Bod-Pod) and fasting blood samples were taken in all evaluations to measure total cholesterol (TC),LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglycerides(TG), glucose and insulin.

GPB was followed by a significant BMI reduction (nadir BMI at 18 m 28.3+0.4 kg/m2 p<0,001) and fat mass decrease(p<0,001). Maximal percentage of excess BMI lost was 84.1%and that of body fat was 87% 18 months after GBP. These numbers decreased to 65.6% and 38.3% (p<0,005 vs nadir) respectively 72 months after the operation, indicating both weight and fat mass regain. TG and LDL-C values decreased 30% with respect to preoperative levels, while HDL-C increased 97%over initial values. This HDL-C increase was progressive even over the weight regain phase. Both TC/HDL-C and TG/HDL-Cratios normalized after GBP and values were sustained over the weight regain period until the end of the study.

These results confirm the beneficial effects of GBP on all lipid fractions, which are maintained over 6 years of follow-up. Globally, the rise in HDL-C seems to be independent of weight or fat mass changes, since it increases even over the weight regain phase, so contributing to a reduction in the prevalence of dyslipidaemia and to cardiovascular risk reduction.