Background <p>Differences in abdominal fat and muscle composition among patients with obesity across glycemic statuses—and the modulatory role of metabolic bariatric surgery (MBS) on these interrelationships—remain unclear. This study thus aims to elucidate the interplay between body composition and glycemic status, and to assess how MBS differentially impacts metabolic parameters and body composition outcomes in these patient groups.</p> Methods <p>In this single-center prospective study, 49 patients with obesity (31 with impaired glucose metabolism [IGM], 18 with normal glucose tolerance [NGT]) underwent Dixon MRI for fat/water separation to assess pancreatic, hepatic, and muscle fat. Measurements were taken preoperatively and 3 months post-laparoscopic sleeve gastrectomy.</p> Results <p>The study included 18 patients with NGT (2 male/16 female; mean age 26.22 ± 7.17 years) and 31 with IGM (16 male/15 female; mean age 33.52 ± 10.65years). Both groups showed significant postoperative reductions in all measured parameters (<i>P</i> &lt; 0.0001). The IGM group demonstrated greater decreases in visceral fat (88.33 ± 38.33 vs. 54.68 ± 25.91 cm², <i>P</i> = 0.001), hepatic fat (13.27 ± 7.00% vs. 8.93 ± 6.69%, <i>P</i> = 0.039), pancreatic fat (13.27 ± 7.00% vs. 8.93 ± 6.69%, <i>P</i> = 0.021), and psoas area (6.13 ± 4.82 vs. 2.18 ± 6.00 cm², <i>P</i> = 0.015) compared to the NGT group. Liver fat correlated positively with HOMA-IR, fasting glucose, and HbA1c (<i>P</i> &lt; 0.05).</p> Conclusions <p>Patients with obesity and IGM have higher visceral fat, pancreatic fat, and erector spinae mass than their NGT counterparts. Following bariatric surgery, they experience greater reductions in liver fat, pancreatic fat, and muscle areas. These findings suggest differential metabolic effects based on preoperative glucose status. However, further large-scale studies are needed to confirm.</p> Graphical Abstract <p></p>