INTRODUCTION: Obesity is the most common metabolic problem and its genesis and maintenance there is always a positive energy balance, with less energy expenditure than that obtained from the intake. Low physical activity is often an important factor in this lower spending. Medical advice is useful for determining changes in the habits of life of patients, however, the changes produced by the council do not last over time, so it would be necessary to establish enforcement mechanisms as with mobile technology, because it could improve the adhesion of obese patients to therapy. OBJECTIVE: Primary: To evaluate the effectiveness of an app as an adjunct to medical advice to promote healthy living habits (sport and diet) to lose weight in a population of obese or overweight adult patients. MATERIAL AND METHODS: Open randomized controlled clinical trial with clinical practice (health advice for physical activity and sport). STUDY POPULATION: Obese or overweight adults patients of Araba aged between 18-45 years who be in Contemplation stage with smartphone. Variables: Primary endpoint: Weight (kg); Secondary variables: BMI (kg/cm2); blood pressure (mm Hg); heart rate; Plasma cholesterol (mg / dl); HbA1c; score on the satisfaction questionnaire; index of physical exercise (IPAQ) (METs); quitting tobacco (yes / no); Waist circumference (cm). Statistical analysis: The primary endpoint (weight reduction) will be evaluated by covariance analysis adjusting by baseline weight, and other confounding variables (sex, age, level of education..) Simple size: 48 patients by arm plus 20% to cover losses to follow.

Inclusion Criteria:

• BMI> = 25 mg / kg
• Holder smartphone
• Sign informed consent

Exclusion Criteria:

• Presence of physical or mental illnesses that prevent the realization of physical activity
• Be participating in another research project
• Pregnancy or lactation
• Patients who are on diet or drug treatment for weight loss
• History of myocardial infarction or stroke