Mechanisms underlying the weight loss effects of RYGB and SG: similar, yet different
A Pucci, R L Batterham, A Pucci, R L Batterham
Abstract
The worldwide obesity epidemic continues unabated, adversely impacting upon global health and economies. People with severe obesity suffer the greatest adverse health consequences with reduced life expectancy. Currently, bariatric surgery is the most effective treatment for people with severe obesity, resulting in marked sustained weight loss, improved obesity-associated comorbidities and reduced mortality. Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), the most common bariatric procedures undertaken globally, engender weight loss and metabolic improvements by mechanisms other than restriction and malabsorption. It is now clear that a plethora of gastrointestinal (GI) tract-derived signals plays a critical role in energy and glucose regulation. SG and RYGB, which alter GI anatomy and nutrient flow, impact upon these GI signals ultimately leading to weight loss and metabolic improvements. However, whilst highly effective overall, at individual level, post-operative outcomes are highly variable, with a proportion of patients experiencing poor long-term weight loss outcome and gaining little health benefit. RYGB and SG are markedly different anatomically and thus differentially impact upon GI signalling and bodyweight regulation. Here, we review the mechanisms proposed to cause weight loss following RYGB and SG. We highlight similarities and differences between these two procedures with a focus on gut hormones, bile acids and gut microbiota. A greater understanding of these procedure-related mechanisms will allow surgical procedure choice to be tailored to the individual to maximise post-surgery health outcomes and will facilitate the discovery of non-surgical treatments for people with obesity.
Keywords: Bile acids; Gut hormones; Gut microbiota; Roux-en-Y gastric bypass; Sleeve gastrectomy; Type 2 diabetes.
Conflict of interest statement
Conflict of interestAll authors declare that they have no conflict of interest.
Ethical approvalAll procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consentInformed consent was obtained from all individual participants included in the studies performed by the authors.
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