All Bariatric Surgeries Are Not Created Equal: Insights from Mechanistic Comparisons

Abstract

Despite considerable scientific progress on the biological systems that regulate energy balance, we have made precious little headway in providing new treatments to curb the obesity epidemic. Diet and exercise are the most popular treatment options for obesity, but rarely are they sufficient to produce long-term weight loss. Bariatric surgery, on the other hand, results in dramatic, sustained weight loss and for this reason has gained increasing popularity as a treatment modality for obesity. At least some surgical approaches also reduce obesity-related comorbidities including type 2 diabetes and hyperlipidemia. This success puts a premium on understanding how these surgeries exert their effects. This review focuses on the growing human and animal model literature addressing the underlying mechanisms. We compare three common procedures: Roux-en-Y Gastric Bypass (RYGB), vertical sleeve gastrectomy (VSG), and adjustable gastric banding (AGB). Although many would group together VSG and AGB as restrictive procedures of the stomach, VSG is more like RYGB than AGB in its effects on a host of endpoints including intake, food choice, glucose regulation, lipids and gut hormone secretion. Our strong belief is that to advance our understanding of these procedures, it is necessary to group bariatric procedures not on the basis of surgical similarity but rather on how they affect key physiological variables. This will allow for greater mechanistic insight into how bariatric surgery works, making it possible to help patients better choose the best possible procedure and to develop new therapeutic strategies that can help a larger portion of the obese population.

Surgical Management of Obesity and the Relationship to Cardiovascular Disease

“…[94][95][96][97][98][99][100][101][102] Head-tohead comparisons of metabolic impact confirm the superiority of malabsorptive over gastric volume reduction surgeries, albeit at the expense of a greater perioperative risk and higher likelihood of malnutrition. However, meta-analyses of the LAGB versus RYGB data highlight the excess of late (≥30 days) complications and the need for reoperation for LAGB patients.…”

Roux-en-Y gastric bypass: effects on feeding behavior and underlying mechanisms

“…An accumulating body of research in animal models corroborates many of the feeding behavior changes observed following RYGBP (105). However, these animal studies should be interpreted with caution due to important differences in the rodent stomach and rodent feeding behavior (106,107), both of which could adversely affect interpretation of RYGBP-induced outcomes.…”

“…Additionally, gender-specific mechanistic studies involving genotype-stratified and obesity phenotype-matched subjects would greatly enhance this field of research. Studies comparing RYGBP with SG, another metabolic procedure with differential biological effects from those of RYGBP (66,88,105,127,128), might also yield important insights into the mechanisms underlying the changes in food preference, hedonic feeding, and neural responsivity. Future research might also employ these bariatric procedures, using a Mendelian randomization experimental approach, as a tool to probe the physiological and genetic mechanisms underlying obesity.…”

Treatment of obesity and diabetes with bariatric surgery

“…We recommend a recent review by Stefater et al, which provides an extensive discussion on the current understanding of the mechanisms of RYGB, LAGB, and LSG [27]. Interstingly, they propose that current evidence shows LSG to be more similar in action to RYGB, rather than LAGB.…”