Background : Obesity is one of the main causes of glycemic change. Failure of clinical obesity treatment may lead to an increase in bariatric surgery. Dietary guidance, in conjunction with disabsorptive and hormonal factors resulting from the anatomical and physiological changes provoked by the surgery, is associated with changes in food intake. Aim: To analyze food intake evolution during the first postoperative year of Roux-en-y gastric bypass in patients with type 2 diabetes mellitus or glycemic alteration. Methods : This was a longitudinal and retrospective observational study. For food intake evolution analysis, linear regression models with normal errors were adjusted for each of the nutrients. Results: At 12 months, all patients presented improvement in glycemic levels (p<0.05). During the first postoperative year, there was a reduction in energy intake, macronutrients, consumption of alcoholic beverages and soft drinks. Conversely, there was an increase in fiber intake and diet fractionation. It was observed that, despite gastric restrictions, the micronutrient intake specifically recommended for glycemic control was greater up to six months postoperatively. Conclusion: There was change in the quantity and quality of food intake. It was the most prevalent glycemic control contributor up to six months postoperatively. At the end of one year, the diet underwent a change, showing a similar tendency to the preoperative food intake pattern.