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Ultra-processed food consumption and body mass index from adolescence to early adulthood: multi-trajectory analysis using data from the 1993 Pelotas (Brazil) birth cohort
This longitudinal study analyzed data from the 1993 Pelotas Birth Cohort in Brazil to identify joint trajectories of ultra-processed food (UPF) consumption and body mass index (BMI) from adolescence to early adulthood, following 2,890 participants at ages 15, 18, and 22 years. Dietary intake was assessed at each follow-up using Food Frequency Questionnaires covering 16 UPF items classified according to the NOVA system and grouped into six categories (fast food, soft drinks, candies, snacks, processed meats, and dairy products), with BMI standardized against WHO growth references and joint trajectories modeled using group-based multi-trajectory analysis stratified by sex.
Three trajectory groups emerged for each sex: two groups showed low UPF consumption over time, while a third group (21.9% of males; 21.5% of females) showed increasing and persistently high UPF consumption, with intake rising most sharply for fast food, soft drinks, and processed meats. Notably, this high-UPF group did not consistently show the highest BMI; among males, group 3’s BMI z-scores remained close to the normal range despite consuming a median of 6 daily UPF items at ages 18 and 22, while high-BMI trajectories occurred in groups with lower UPF intake — suggesting that BMI alone does not capture unhealthy dietary patterns.
Group 3 also showed disproportionate accumulation of co-occurring risk behaviors, including increases in alcohol use (males: 47.3% → 81.1%; females: 56.0% → 71.3%), smoking (males: 11.6% → 41.7%; females: 19.7% → 31.9%), high screen time, and clustering of at least two risk behaviors, indicating that UPF consumption may identify vulnerable youth before excess weight becomes evident and that adolescent health monitoring should extend beyond BMI to capture dietary and behavioral risk patterns relevant to future nutritional and psychosocial outcomes. [NPID: ultra-processed food, UPF, adolescents, early adulthood, BMI, NOVA classification, longitudinal study, birth cohort, Brazil, risk behaviors, dietary trajectories]
Year: 2026
