Recent findings from a study published in JAMA Surgery reveal that gastric bypass surgery (RYGB) offers significant improvements in atherogenic blood lipids such as LDL cholesterol and apolipoprotein B (apoB), independent of weight loss and caloric restriction. This research challenges the conventional belief that these benefits are solely attributed to weight loss and calorie reduction.
Study Overview and Findings
The study, known as the COCKTAIL study, involved 78 patients with severe obesity who were treated either with RYGB plus a very-low-calorie diet or a very-low-calorie diet alone. Both groups initially followed a calorie intake of approximately 1,200 kcal/day. After three weeks, the diet group continued on a very-low-calorie diet (around 800 kcal/day), while the RYGB group underwent surgery and continued the same low-calorie diet.
In the first three weeks, both groups showed significant improvements in body weight, fat mass, HbA1c levels, systolic blood pressure, and LDL cholesterol, with no significant differences between them. However, during the subsequent six-week period, the RYGB group experienced more substantial reductions in LDL cholesterol, non-HDL cholesterol, apoB, and lipoprotein(a) compared to the diet-only group. Notably, while the RYGB group saw a decline in total, LDL, and non-HDL cholesterol levels, the diet-only group’s levels either stabilized or slightly increased.
Understanding the Lipid-Lowering Effect
Senior investigator Dr. Jøran Hjelmesæth emphasized that the study aimed to discern whether the improvements in lipid profiles were due to the surgery itself, caloric restriction, or weight loss. The results suggest that the beneficial effects on lipid levels are attributable to the surgery rather than just the associated weight loss and calorie restriction. This finding is significant because it highlights that RYGB has direct effects on lipid metabolism that are independent of changes in body weight.
Dr. Hjelmesæth noted that previous studies did not account for weight loss or caloric restriction, which led many experts to assume that the improvements in cardiovascular risk factors were a result of weight loss alone. This study, however, provides evidence that gastric bypass surgery itself contributes to favorable changes in lipid levels.
Comparing with Emerging Treatments
In light of advancements in obesity treatment, particularly with the introduction of glucagon-like peptide-1 (GLP-1) receptor agonists, some experts question the relevance of these findings. Dr. Leah Schoel and Dr. Dana Telem from the University of Michigan suggest that future studies should evaluate the comparative benefits of GLP-1 receptor agonists and bariatric surgery. They argue that both treatments play crucial roles in obesity management and that understanding their relative benefits and cost-effectiveness is essential for comprehensive treatment strategies.
Dr. Hjelmesæth acknowledged the need for further research to compare GLP-1 receptor agonists with bariatric surgery, noting that these drugs primarily impact blood glucose and insulin levels, with only a modest effect on lipid profiles.
Conclusion
The COCKTAIL study underscores that gastric bypass surgery can independently improve lipid profiles, offering a direct benefit beyond weight loss and caloric restriction. This revelation adds a new dimension to the understanding of how bariatric surgery influences cardiovascular health. As the field of obesity treatment evolves, integrating insights from such studies with emerging therapies will be crucial in optimizing patient care and outcomes.
