Introduction. We propose the following hypothesis: ultra processed foods in the global food supply contribute to the worldwide increase in obesity.Objective. To analyze the association between a higher consumption of ultra processed foods and the obesity in adulthood in the United States. Materials and methods. United States National Survey of Health and Nutrition Examination (NHANES) (2009-2018) data were used. We included subjects of both sexes, aged between 18-64 years old, with anthropometric, health, income, race/ethnicity and physical activity (PA) data. The association between the ultra processed food intake and obesity was calculated using a binomial logistic regression. In addition, we also evaluated a subsample with subjects who did not consume more than their adequate daily energy requirements.Results. We evaluated 13,310 subjects in total, and 4,788 in our subsample. Of these 33% were committed to obesity, and in the subsample the prevalence was even higher, around 49%. In our analysis, we found five factors (ultraprocessed food consumption, sex, age, race/ethnicity,and sedentary lifestyle) that were positively associated with the development of obesity.Compared to subjects who consumed less than 20% of ultraprocessed foods, subjects whoconsumed between 20 to 40% of ultraprocessed food had 16% more odds of developingobesity [95%CI:1.06-1.26]. For the subsample, the odds were even higher, being around 27%[95%CI:1.11-1.46].Conclusions. Our results showed a positive association between obesity and the amount of ultra processed food consumption, even though, in those who consumed no more than their adequate daily energy requirements