Weight loss dynamics after laparoscopic sleeve gastrectomy: a retrospective single center analysis with age and preoperative weight stratification

Laparoscopic Sleeve Gastrectomy (LSG) is the most common bariatric procedure worldwide. However, the influence of preoperative factors on weight loss outcomes remains incompletely understood. We investigated the effects of preoperative weight, height, and age on total weight loss percentage (%TWL) following LSG using advanced statistical modeling. 2014 LSG patients were analyzed and stratified by preoperative weight (7 categories: <90 kg to > 160 kg) and age (5 groups: 14-25 to ≥ 56 years). %TWL was calculated at 1 week, 1, 3, 6, and 12 months post-surgery. A Generalized Additive Model (GAM) was used to calculate Adjusted Total Weight Loss percentage (%ATWL), accounting for height and preoperative weight confounding effects. The population (mean age: 38.0 ± 11.4 years, BMI: 42.9 ± 8.2 kg/m²) showed weight-dependent %TWL at 12 months, from 32.2%±10.0% (< 90 kg) to 39.8%±7.5% (> 160 kg) (p < 0.001). GAM-adjusted %ATWL revealed superior outcomes in younger cohorts. The 14-25 and 26-35 year groups had comparable 12-month %ATWL (38.2% vs. 37.0%, p = 0.222), significantly exceeding older groups (p < 0.001). Early postoperative %ATWL (1-week) was similar across ages (4.6-5.7%), with progressive differentiation at 3, 6, and 12 months. Preoperative weight and age significantly influence LSG weight loss outcomes. Younger patients and those with higher pre-op weights achieved greater 12-month %TWL.