OBJECTIVES: The aim of this study was to evaluate the relationship between the consumption of ultra-processed foods and obesity indicators among Brazilian adults and adolescents. METHODS: We used cross-sectional data on 30,243 individuals aged ≥10 years from the 2008-2009 Brazilian Dietary Survey. Food consumption data were collected through 24-h food records. We classified food items according to characteristics of food processing. Ultra-processed foods were defined as formulations made by the food industry mostly from substances extracted from foods or obtained with the further processing of constituents of foods or through chemical synthesis, with little if any whole food. Examples included candies, cookies, sugar-sweetened beverages, and ready-to-eat dishes. Regression models were fitted to evaluate the association of the consumption of ultra-processed foods (% of energy intake) with body-mass-index, excess weight, and obesity status, controlling for socio-demographic characteristics, smoking, and physical activity. RESULTS: Ultra-processed foods represented 30% of the total energy intake. Those in the highest quintile of consumption of ultra-processed foods had significantly higher body-mass-index (0.94 kg/m(2); 95% CI: 0.42,1.47) and higher odds of being obese (OR=1.98; 95% CI: 1.26,3.12) and excess weight (OR=1.26; 95% CI: 0.95,1.69) compared with those in the lowest quintile of consumption. CONCLUSION: Our findings support the role of ultra-processed foods in the obesity epidemic in Brazil.