Objective: The visceral fat is linked to insulin resistance, the metabolic syndrome, type 2 diabetes and an increased cardiovascular risk, but it is not clear whether it has a causative role.

Design and Methods: Surgical resection of this fat depot is a research model to address this issue. Twenty premenopausal women with metabolic syndrome and grade III obesity were randomized to undergo Roux‐en‐Y gastric bypass (RYGBP) either alone or combined with omentectomy. Insulin sensitivity (IS; euglycemic‐hyperinsulinemic clamp), acute insulin response to glucose (AIR; intravenous glucose tolerance test), disposition index (DI = AIR × IS measured by clamp), lipid profile, adipokine profile (leptin, adiponectin, resistin, visfatin, interleukin‐6, TNF‐α, MCP‐1), ultra‐sensitive C‐reactive protein (CRP), body composition, and abdominal fat echography were assessed prior to surgery and 1, 6, and 12 months post‐surgery.

Results: Omentectomy was associated with greater weight loss at all time points. IS improved similarly in both groups. Omentectomy was associated to lower CRP after 12 months, but it did not influence adipokines and other metabolic parameters. Among non‐diabetic subjects, omentectomy was associated with a preservation of baseline AIR after 12 months (as opposed to deterioration in the control group) and a greater DI after 6 and 12 months.

Conclusion: Although omentectomy did not enhance the effect of RYGBP on insulin sensitivity and adipokines, it was associated with a preservation of insulin secretion, a greater weight loss, and lower CRP.