OR10-06 Changes In Resting Energy Expenditure And Metabolic Adaptation In Adolescents Two Years After Sleeve Gastrectomy Compared With Non-surgical Controls And Determinants Of These Changes

Disclosure: V. Singhal: None. C.C. Pedreira: None. S. Tuli: None. L.A. Haidar: None. H. Lee: None. M.A. Bredella: None. M. Misra: None. Background: Weight loss is typically associated with reductions in resting energy expenditure (REE), which may limit the extent of weight loss after sleeve gastrectomy (SG), the most common metabolic and bariatric surgery (MBS) in youth. REE may be impacted by changes in body composition and gut peptides following SG. Current data regarding changes in measured REE (mREE) and metabolic adaptations in adolescents after MBS are limited. Objectives: To evaluate changes in mREE, estimated REE (eREE), metabolic adaptation (difference in mREE – eREE), body composition, and gut peptides in youth after SG compared to non-surgical controls (NS) over two years. Methods: Youth 14-22 years old undergoing SG (n=24) and NS controls with severe obesity (n=28) were enrolled in this study. mREE was determined by indirect calorimetry. The Mifflin equation was used to calculate eREE. To account for effects of changes in FFM and total body weight (TBW), we evaluated mREE/FFM, mREE/TBW, eREE/FFM, and eREE/TBW. Dual energy X-ray absorptiometry (DXA) was used to measure body composition. Fasting plasma levels of ghrelin, peptide YY (PYY), glucagon-like peptide 1 (GLP-1), and insulin were measured. All measurements were performed at baseline and two years later. Results: Mean age and sex did not differ across groups. Body mass index (BMI) at baseline trended higher in SG vs. NS [43.60 (39.81, 49.39) vs. 41.60 (37.83, 48.21) kg/m(2), (p=0.051)]. Mean change in BMI was higher in SG than NS (–11.5 ± 1.21 vs. 1.47 ± 0.58 kg/m(2), p<0.0001). SG had a within group decrease in mREE of 400.96 ± 69.49 kcal/d (p<0.0001) and in eREE of 325.68 ± 34.73 kcal/d (p<0.0001) over 2 years. While mREE and eREE decreased in SG, both measures increased in NS over 2 years (p<0.0001 for both). Changes in mREE/FFM, mREE/TBW, and eREE/FFM over 2 years did not differ between groups (p=0.14, 0.24 and 0.61 respectively) while eREE/TBW increased in SG and decreased in NS (p< 0.0001). Metabolic adaptation over 2 years did not differ between groups (p=0.335). Ghrelin and insulin levels decreased over 2 years following SG but PYY and GLP-1 did not change significantly. Within SG, metabolic adaptation was positively associated with 2-year change in FFM (Spearman ρ= 0.57 p=0.009), but not with changes in gut peptides over 2 years. Conclusion: Despite significant decreases in BMI after SG in youth, surgical and non-surgical groups did not differ for changes in mREE/FFM and metabolic adaptation over 2 years. Presentation: Friday, June 16, 2023