Introduction: A sedentary lifestyle and the consumption of unhealthy foods are associated with overweight and obesity in the population. The consumption of fruits, vegetables and legumes has decreased over time and a large part of the Chilean population does not meet the daily intake recommendations. Objective: To determine the relationship between the BMI of Chilean adults and the consumption and frequency of various natural, processed, and ultra-processed foods. Methodology: Analytical cross-sectional study in 516 subjects between 18 and 68 years of age. Nutritional status was determined by means of BMI. To analyze the consumption of natural foods and processed food, the survey on eating habits was used. The participants signed an informed consent. The values obtained were analyzed with the statistical program SPSS (R). The results obtained were analyzed using T-Student, Pearson's Chi-square, one-way ANOVA and Fisher's exact test, to define the association between them. Results: 0.8% of those evaluated were classified as low weight; 42.2% with normal nutritional status; 42.8% overweight and 14.0% obese. 37.8% of those evaluated do not consume fruits daily; 22.9% do not consume vegetables during the day and 26.4% do not consume legumes weekly. 39.5% of people drink 1 or more servings of sugary drinks per day and 35.3% consume fried foods 1 or more times per week. A higher consumption of fruits (p=0.04), vegetables (p=0.002) and legumes (p=0.03) was associated with a lower BMI. High consumption of sugary drinks and juices was associated with a higher BMI (p=0.002). Finally, a significant association was found between the consumption of vegetables per day, legumes per week, and sweetened juices with respect to nutritional status (95% confidence). Conclusions: A high frequency of overweight and obesity was observed, accompanied by a low consumption of fruits, vegetables and legumes. Adults who had a higher intake of natural foods had a lower BMI, in contrast to those who had a higher intake of sugary drinks and junk food.