Abstract Background Previous studies link obesity to neurophysiological changes, however cognitive outcomes in adolescents who are overweight or obese, especially with their eating behavior, require further documentation. Objective To examine the association between body mass index (BMI), eating behavior, and cognitive performance in Mexican adolescents. Method Urban Mexican adolescents completed CANTAB tasks assessing spatial memory (PAL: Paired Associates Learning; SSP: Spatial Span), verbal memory (VRM: Verbal Recognition Memory), and emotional recognition (ERT: Emotion Recognition Task), as well as eating behavior measures. Cognitive performance was compared between normal-weight and overweight and obesity groups. Hierarchical regressions tested BMI and eating disorder symptoms as predictors of cognition. Results The overweight and obesity group showed significantly poorer performance on PAL and SSP. Multivariate analyses revealed BMI, sex, and age predicted PAL, SSP, and VRM performance. Eating behavior differed by weight group, but only eating disorder symptoms predicted cognition. Neither BMI nor eating behavior predicted ERT performance. Conclusions Spatial working memory is weaker in adolescents who are overweight or obese. Higher BMI also relates to poorer verbal memory, expanding known executive function deficits. Overall, these data reinforce the evidence on the negative effects of hyperadiposity on cognitive performance in adolescents. © The Author(s) 2026. Published by Oxford University Press.