Prospective study of gut hormone and metabolic changes after laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass

Abstract

Background Laparoscopic sleeve gastrectomy (SG) has surpassed Roux-en-Y gastric bypass (RYGB) as the most prevalent bariatric procedure worldwide. While RYGB and SG demonstrate equivalent short-term weight loss, long-term weight loss tends to be greater after RYGB. Differences in the effect of these procedures on gastrointestinal hormones that regulate energy homeostasis are felt to partially underlie differences in outcomes. The objective of this study was to prospectively quantify blood levels of gut hormones of energy and glucose homeostasis at one year follow up to delineate possible reasons for greater efficacy of RYGB over SG in achieving weight loss. Methods Patients undergoing SG (n = 19) and RYGB (n = 40) were studied before surgery and at 2,12, 26, and 52 weeks postoperatively. Blood samples drawn in the fasted state and after a liquid mixed meal were assayed at baseline, 26, and 52 weeks for peptide YY (PYY), glucagon-like peptide-1 (GLP-1), ghrelin, insulin, glucose, and leptin. Fasting and postprandial appetitive sensations were assessed by visual analog scale. Results At 1 year there was greater weight loss in RYGB compared with SG patients (30% vs 27%; P = 0.03). Area under the curve (AUC) after the mixed meal for PYY was greater in RYGB patients (P<0.001). RYGB patients had significant increases in GLP-1 AUC compared to baseline (P = 0.002). Ghrelin levels decreased only after SG compared to baseline (P<0.001) but were not significantly different from RYGB. There was a trend toward decreased sweet cravings in RYGB patients (P = 0.056).

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

“…Alterations in PYY levels after bariatric surgery [21,32,34,45,83,85,89,91,94,108,114] are described in Table 1. Postprandial PYY levels are elevated after RYGB and SG, with more potent changes after RYGB [34,91,108,114].…”

“…Fasting ↓ [85,87,88,90] or ↔ [33,34,48,88,89,91,92.94,108,114] or ↑ [86][87][88]91,108] Postprandial ↓ [48,85,90] or ↔ [33,34,48,89,94,108,114] or ↑ [89,91] Fasting ↓↓ [23,33,34 [23,33,97,119] Fasting ↔ [23,33] Postprandial ↔ [23] or ↑ [33] Fasting ↔ [33] Postprandial NA…”

The Effects of Oxytocin on Appetite Regulation, Food Intake and Metabolism in Humans

“…Hence, the authors of this study hypothesized that the increase in oxytocin levels induced by probiotic treatment contributed to the improvement in weight management [ 204 ]. Taken together, it can be concluded that studies show inconsistent changes in oxytocin levels following weight reduction, which could be related the different hormonal/metabolic changes associated with each method of bariatric surgery [ 206 ] and the independent mechanisms related to the interaction of probiotic treatment with oxytocin [ 205 ].…”

Leptin Receptors Are Not Required for Roux-en-Y Gastric Bypass Surgery to Normalize Energy and Glucose Homeostasis in Rats

“…Because RYGB mainly reduces fat mass [ 33 ], it is associated with a marked reduction in circulating leptin levels [ 34 , 35 , 36 ]—even beyond chronic caloric restriction-induced weight loss alone [ 37 , 38 , 39 , 40 , 41 , 42 ]. Nevertheless, endogenous leptin action has been proposed to be enhanced postoperatively [ 43 , 44 , 45 , 46 , 47 , 48 ], thereby preventing the powerful counter-regulatory response to depletion of energy stores which normally leads to weight-regain [ 11 , 12 ].…”