OBJECTIVE Changes in liver fatty acid metabolism are important in understanding the mechanisms of diabetes remission and metabolic changes after bariatric surgery.

RESEARCH DESIGN AND METHODS Liver fatty acid uptake (LFU), blood flow, and fat content (LFC) were measured in 25 obese subjects before bariatric surgery and 6 months after using positron emission tomography/computed tomography and MRS; 14 lean individuals served as the control subjects.

RESULTS The increased LFU in obese subjects was associated with body adiposity. LFU was reduced postoperatively but was still high compared with the control subjects. LFC was normalized. Liver blood flow (per unit volume) was higher in obese subjects than in the control subjects at baseline and was further increased postoperatively; however, the total organ blood flow was unchanged as the liver volume decreased.

CONCLUSIONS The findings suggest that in a postoperative state, intrahepatic fatty acids are not stored in the liver but are used for oxidation to provide energy. Changes in perfusion may contribute to improved liver metabolism postoperatively.