The aim of the present study was to study the interdigestive motor complex (MMC), distal small intestinal hormones, and gastric emptying in normal-weight and obese subjects before and after jejunoileal bypass (JIB). Therefore, fasting antroduodenal motility, gastric emptying, and RIA for motilin (MOT), neurotensin (NT), peptide YY (PYY), and glucagon-like peptide-1 (GLP-1) was performed in nine obese subjects before (BMI 42 +/- 4 kg/m2) and nine months after (BMI 31 +/- 4) JIB, and in two groups of nine age- and sex-matched controls (BMI 23 +/- 1 and 21 +/- 1). The rate of gastric emptying was faster in obese subjects and GLP-1 lower compared to normal-weight controls. After JIB, fewer phase III of the MMC were observed; fasting levels of PYY were elevated during the MMC; postprandial levels of NT, PYY, and GLP-1 were elevated; and gastric emptying was delayed. Our results suggest that there may be an association between an impaired GLP-1 response after food intake and obesity, and after JIB, PYY seems to regulate interdigestive motility while GLP-1 may regulate early gastric emptying.