Effect of gastric bypass versus diet on cardiovascular risk factors

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.

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.

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).

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.

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. (NCT01707771).