Inclusion Criteria:  Years: ≥18 Sex: Female Newly diagnosed breast cáncer  Exclusion Criteria:  Patients who have disseminated disease. Associated eating behavior disorders. Patients with dementia, mental illness or decreased cognitive function. Consumption of drugs or substances to lose weight (except in those cases in which it is suspended 15 days before starting the study). Presence of disease that may interfere with weight loss: severe psychiatric illness, uncontrolled hypothyroidism. Pregnant or breastfeeding women.