Obesity is an important nutritional deviation that is exponentially increasing in Brazil and in the world, becoming a public health problem. The World Health Organization verified in 2005 that 1.6 billion people above 15 years old were overweight and 400 million were obese. Among children, 20 million were overweight. Amongst the different treatments for the obesity the bariatric surgery has been used very often nowadays, for being effective against weight excess and associated co-morbidities, both for the adult and youngster populations. The surgical techniques are divided in restrictive, disabsorptive and mixed procedures. Each technique promotes digestive and absorptive distinct alterations, needing, therefore, an exclusive multidisciplinary educational program, directed both to pre and postsurgery periods, emphasizing the habits of physical activity and the necessity to adhere to the restricted dietary recommendations. The surgeries promote a severe reduction in the consumption, which induces to the ingestion of diets that are hypocaloric and deficient in micronutrients, with consequent nutritional complications.