Roux-en-Y Gastric Bypass Surgery Has Unique Effects on Postprandial FGF21 but Not FGF19 Secretion

Fibroblast growth factor (FGF)19 and FGF21 are secreted by the intestine and liver in response to macronutrient intake. Intestinal resection and reconstruction via bariatric surgery may alter their regulation.

We tested the hypothesis that weight loss induced by Roux-en-Y gastric bypass (RYGB) surgery, but not matched weight loss induced by laparoscopic adjustable gastric banding (LAGB), increases postprandial plasma FGF19 and FGF21 concentrations.

Glucose kinetics and plasma FGF19 and FGF21 responses to mixed meal ingestion and to glucose-insulin infusion during a hyperinsulinemic-euglycemic clamp procedure, with stable isotope tracer methods, were evaluated in 28 adults with obesity before and after 20% weight loss induced by RYGB (n = 16) or LAGB (n = 12).

LAGB- and RYGB-induced weight loss increased postprandial plasma FGF19 concentrations (P < 0.05). However, weight loss after RYGB, but not LAGB, increased postprandial plasma FGF21 concentrations (1875 ± 330 to 2976 ± 682 vs 2150 ± 310 and 1572 ± 265 pg/mL × 6 hours, respectively). The increase in plasma FGF21 occurred ∼2 hours after the peak in delivery of ingested glucose into systemic circulation. Glucose-insulin infusion increased plasma FGF21, but not FGF19, concentrations. The increase in plasma FGF21 during glucose-insulin infusion was greater after than before weight loss in both surgery groups without a difference between groups, whereas plasma FGF19 was not affected by either procedure.

RYGB-induced weight loss has unique effects on postprandial FGF21 metabolism, presumably due to rapid delivery of ingested macronutrients to the small intestine and delivery of glucose to the liver.