Effect of Gastric Bypass Versus Diet on Cardiovascular Risk Factors

OBJECTIVE: To assess the effect of Roux-en-Y gastric bypass (RYGB) on high-density lipoprotein cholesterol (HDL-C) concentration and its apolipoprotein A4 (ApoA4) content at 1 year after bariatric surgery in comparison with a hypocaloric diet. Secondary aim was to measure total cholesterol and triglycerides levels and insulin sensitivity after interventions. BACKGROUND: Very few prospective uncontrolled studies have investigated the effects of RYGB on cardiovascular risk factors. No controlled studies had as primary goal the changes in HDL-C after gastric bypass. METHODS: Forty subjects with a body mass index more than 40 or 35 kg/m or more in the presence of diabetes were enrolled. Twenty of them underwent RYGB, whereas 20 received lifestyle modification suggestions and medical therapy for obesity complications (diabetes, hypertension, and hyperlipidemia). RESULTS: A significant (P < 0.0001) increase in HDL-C concentrations was observed only in the surgical arm (from 41.95 ± 7.24 to 56.55 ± 9.01 mg/dL). Mean systolic and diastolic blood pressures were significantly reduced (P < 0.0001) in both groups with no between-group differences, probably in relation to the optimization of the antihypertensive treatment. Plasma concentration of ApoA4, a major HDL-C protein fraction, significantly increased 1 year after RYGB (from 496.61 ± 400.41 to 987.88 ± 637.41μg/L, P < 0.01). Circulating triglycerides concentration significantly decreased after surgery, whereas both peripheral and hepatic insulin resistance increased significantly. CONCLUSIONS: Our study shows that HDL-C and ApoA4 significantly increase after gastric bypass and that this increase is associated with a net improvement in hepatic insulin sensitivity. Furthermore, we speculate that ApoA4, which induces satiety in animals, can eventually play a role on the appetite reduction after RYGB because there is a strict and inverse relationship between weight and ApoA4 changes.