Laparoscopic sleeve gastrectomy (LSG) is an important therapeutic option for morbidly obese patients. Although LSG promotes sufficient weight loss, how LSG changes plasma metabolites remains unclear. We assessed changes in plasma metabolite levels after LSG. We collected plasma samples from 15 morbidly obese Japanese patients before and 3 months after LSG. Forty-eight metabolites were quantified using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS)-based metabolomic profiling. Branched chain amino acids, several essential amino acids, choline, 2-hydroxybutyric acid, 2-oxoisovaleric acid, and hypoxanthine were significantly decreased after LSG. Tricarboxylic acid cycle metabolites, including citric acid, succinic acid, and malic acid, were significantly elevated after LSG. This is the first report to show dynamic alterations in plasma metabolite concentrations, as assessed using CE-TOFMS, in morbidly obese patients following LSG. Our results may reveal how LSG helps improve obesity, in part through metabolic status changes, and propose novel therapeutic targets to ameliorate obesity.This article is protected by copyright. All rights reserved.