Objectives: To evaluate the cognitive performance of obese patients with MCI and the effect of weight loss induced by caloric restriction on cognition, conversion to dementia, to assess weight loss, changes in inflammatory and metabolic parameters, change in physical capacity, performance in neuropsychological tests and correlate with effects of the intervention. Methods: The patients will be randomized to two groups that will be followed for 12 months. The control group will receive conventional medical care. The intervention group will receive nutritional counseling individually and in groups, aiming to promote weight loss (10% of body weight) through caloric restriction, and medical monitoring. Everyone will be advised to physical activity. Before and after 12 months patients will be evaluated for anthropometry, body composition, physical performance, control of comorbidities, laboratory tests (glucose, insulin, lipid profile, leptin, adiponectin, interleukin 6, tumor necrosis factor alpha, CRP), Genotyping apolipoprotein E, neuropsychological battery, questionnaires about activities of daily living, physical activity and diet.