Healthy vs. Unhealthy Snacks: Impact on Obesity Risk Among Mexican Adolescents. Results from a cross-sectional study.

Background: Snacking during adolescence has been identified as both a risk and a protective factor for obesity. The type, frequency, and quantity of snack intake may determine their health impact. This study evaluated school snack intake by type (healthy vs. unhealthy) and its association with obesity risk. Methods: A Snack and Beverage Frequency Questionnaire (SBFQ) was adapted and applied to 397 Mexican adolescents aged 15–18 years. Snack intake was estimated in grams and compared according to BMI-for-age z-score categories (adequate vs. excess weight). BMI-for-age z-score was correlated with adiposity indicators using Spearman’s coefficient. For regression analyses, snack variables were dichotomized (0/1) based on daily portion recommendations. Multivariable Poisson regression models with robust standard errors were adjusted for age and sex. Results: BMI-for-age z-score showed strong positive correlations with waist circumference, hip circumference, waist-to-height ratio, and body fat percentage (all p < 0.001). No significant associations were observed between healthy snack intake and excess weight. Among unhealthy snacks, sweet bread intake was significantly associated with BMI-for-age category (IRR = 0.67; 95% CI: 0.49–0.91; p = 0.011), while other snack categories showed no significant associations. Conclusion: In this sample of Mexican adolescents, snack intake classified according to daily portion recommendations was not consistently associated with obesity risk. These findings suggest that isolated snack consumption during school hours may have limited impact on BMI when total dietary intake is not assessed. Comprehensive evaluation of overall dietary patterns may be necessary to better understand the role of snacks in adolescent obesity.