Fasting Plasma Ghrelin Concentrations 6 Months after Gastric Bypass are not Determined by Weight Loss or Changes in Insulinemia

Background: Ghrelin is a gastric peptide with potent orexigenic effects. Circulating ghrelin concentrations are increased in obese subjects, but increase after weight loss. However, in patients undergoing Roux-en-Y gastric bypass (RYGBP), a decrease in ghrelin levels has been reported. The effect of comparable weight loss induced by either adjustable gastric banding (AGB), RYGBP or conventional dietary treatment (Conv) on ghrelinemia was studied. Methods: 24 matched obese male patients in whom similar weight loss had been achieved by either AGB (n=8), RYGBP (n=8) or Conv (n=8) were studied before and 6 months after treatment start. The independence of ghrelin concentrations from body mass index (BMI) and weight loss was further analyzed in a group of patients with total gastrectomy (TtGx, n=6). Results: Comparable weight loss after 6 months exerted significantly different effects on plasma ghrelin concentrations, depending on the procedure applied (AGB: 424.6 ± 32.8 pg/ml; RYGBP: 131.4 ± 13.5; Conv: 457.3 ± 18.7; P<0.001). Without significant differences in body weight and BMI, patients who had undergone the RYGBP exhibited a statistically significant decrease in fasting ghrelin concentrations, while the other two procedures (AGB and Conv) showed a weight loss-induced increase in ghrelin levels. Despite significant differences in BMI between RYGBP and TtGx patients after 6 months (31.9 ± 2.2 vs 22.0 ± 0.7 kg/m², respectively; P<0.05), both groups showed similar ghrelin concentrations. Conclusion: The reduction in circulating ghrelin concentrations in RYGBP patients after 6 months of surgery are not determined by an active weight loss or an improved insulin-sensitivity but rather depend on the surgically-induced bypass of the ghrelin-producing cell population of the fundus.