Abstract Body: Background: Small, short-term feeding trials show that ultra-processed food consumption promotes moderate weight gain. However, the long-term consequences of ultra-processed food consumption on obesity risk in the general population are not well characterized.

Methods: We conducted a prospective cohort analysis in middle-aged adults without obesity in the Atherosclerosis Risk in Communities study. Body mass index (BMI) was assessed at baseline (1987-1989) and 3 subsequent visits (1990-1992, 1993-1995, and 1996-1998). Ultra-processed food was defined according to the Nova classification from a 66-item self-reported food frequency questionnaire. We used complementary log-log models to examine the association between ultra-processed food consumption (modeled as residual-adjusted quartiles and as continuous linear exposure) and incident obesity (BMI ≧ 30 kg/m²). We also used a restricted cubic spline to more flexibly model the association between ultra-processed food and obesity.

Results: Among 10,171 participants (mean age of 54 years, 17% Black adults, 53% female), there were 1,716 cases of incident obesity over a median follow-up of 9 years. Greater ultra-processed food consumption was associated with a higher risk of obesity (Figure A). Each additional serving of ultra-processed food was associated with 4% higher risk of incident obesity (HR = 1.04, 95% CI: 1.01 – 1.06). After adjustment for covariates, individuals in the highest quartile of ultra-processed food consumption had a 22% higher risk of obesity compared to those in the lowest quartile (HR = 1.22, 95% CI: 1.06 – 1.40, p-trend=0.01). Associations between subgroups of ultra-processed food and obesity were strongest for sugar-sweetened beverages followed by reconstituted meat (Figure B).

Conclusion: Excess ultra-processed food consumption, particularly sugar-sweetened beverages and reconstituted meat, was associated with a substantially higher risk of obesity. Policies and strategies aimed at limiting consumption of harmful ultra-processed food are critical for obesity prevention.