For the significant minority of adolescents who regain weight or fail to reach healthy BMI targets after bariatric surgery, pharmacological adjuncts represent one of the few remaining clinical options. Understanding precisely how those agents alter eating behavior — not just weight outcomes — matters enormously for guiding combination therapies in this vulnerable population.

This secondary analysis from a pilot randomized trial enrolled 27 adolescents (mean age 18.1 years, mean BMI 40.4 kg/m²) who remained in the obese range at least one year after vertical sleeve gastrectomy. Participants completed standardized buffet meals — a controlled, objective measure of ad libitum intake — before and after four months of liraglutide treatment. Energy intake fell by a mean of approximately 162 kcal per eating occasion, and total food mass declined by roughly 72 grams. Notably, macronutrient proportions were unchanged, meaning liraglutide produced a uniform suppression of eating rather than selective reductions in fat or carbohydrate. Liraglutide plasma exposure, quantified via LC-MS/MS area-under-the-curve, showed no significant relationship with the degree of energy intake reduction, nor did glucose tolerance metrics from a concurrent oral glucose tolerance test.

Several contextual points deserve attention. The sample of 27 completers is modest, limiting statistical power to detect associations between drug exposure and appetite outcomes — a finding that would have been clinically informative for dose optimization. The buffet meal paradigm captures a single eating occasion and may not fully reflect free-living dietary behavior over months. Additionally, the disconnect between caloric reduction and the absence of a statistically significant weight-change association suggests that 162 kcal per meal may be insufficient to drive meaningful BMI shifts in this surgically altered cohort, or that compensatory intake occurs at other meals. This aligns with growing evidence that GLP-1 receptor agonists produce heterogeneous appetite responses post-bariatric surgery, potentially because VSG itself amplifies endogenous GLP-1 secretion, narrowing the pharmacodynamic margin for exogenous liraglutide. Overall, this is incremental but directionally useful evidence supporting adjunct GLP-1 therapy in post-surgical adolescent obesity.