Do Gut Hormones Contribute to Weight Loss and Glycaemic Outcomes after Bariatric Surgery?

Abstract

Bariatric surgery is an effective intervention for management of obesity through treating dysregulated appetite and achieving long-term weight loss maintenance. Moreover, significant changes in glucose homeostasis are observed after bariatric surgery including, in some cases, type 2 diabetes remission from the early postoperative period and postprandial hypoglycaemia. Levels of a number of gut hormones are dramatically increased from the early period after Roux-en-Y gastric bypass and sleeve gastrectomy—the two most commonly performed bariatric procedures—and they have been suggested as important mediators of the observed changes in eating behaviour and glucose homeostasis postoperatively. In this review, we summarise the current evidence from human studies on the alterations of gut hormones after bariatric surgery and their impact on clinical outcomes postoperatively. Studies which assess the role of gut hormones after bariatric surgery on food intake, hunger, satiety and glucose homeostasis through octreotide use (a non-specific inhibitor of gut hormone secretion) as well as with exendin 9–39 (a specific glucagon-like peptide-1 receptor antagonist) are reviewed. The potential use of gut hormones as biomarkers of successful outcomes of bariatric surgery is also evaluated.

Mechanisms of Weight Loss After Obesity Surgery

“…Changes to plasma concentration of the orexigenic hormone ghrelin after RYGB remains controversial. Studies in humans have demonstrated that hormone levels are increased, decreased or stay the same 97 . The results of studies measuring ghrelin after VSG are more consistently demonstrating a decrease in the postprandial concentrations of the hormone 97 .…”

“…Studies in humans have demonstrated that hormone levels are increased, decreased or stay the same 97 . The results of studies measuring ghrelin after VSG are more consistently demonstrating a decrease in the postprandial concentrations of the hormone 97 . Thus, the contribution of ghrelin reductions in weight loss might be more relevant after VSG than RYGB.…”

Metabolic Profiling of Type 2 Diabetes Patients after Bariatric Surgery by Raman Spectroscopy

“…To date, BS includes different types of interventions: restrictive, hypo-absorptive, malabsorptive, and all three combined, with each intervention affecting the hormonal and glyco-metabolic profile in a different way [10,11].…”

“…BS guarantees rapid and considerable weight loss and significantly reduces calorie intake [9][10][11]. In addition, changes in the entero-hormonal pattern after BS play a decisive role in decreasing postprandial glycaemia and increasing insulin secretion.…”

Appetite and Satiety Control—Contribution of Gut Mechanisms

“…That bariatric surgery is the most effective strategy to achieve long-term weight loss in obesity is likely to be attributable to the markedly enhanced secretion of some gut hormones. Papamargaritis and le Roux discuss current knowledge derived from clinical studies relating to the effects of bariatric surgery on gut hormones and its associated effects to reduce food intake and suppress appetite [ 26 ]. In contrast to obesity, which is characterised by relative overconsumption of food, ‘healthy’ ageing is associated with a decline in hunger and the desire to eat, making individuals more susceptible (e.g., as a result of intercurrent illness) to malnutrition and a loss of bodily function, particularly of muscle.…”