In order to explain obesity surgery and its need we first have to answer the question what obesity is. Obesity is the excess of body weight relative to height above the desired level as a result of excessive increase in the ratio of body fat mass to lean mass. Adipose tissue constitutes 15-18% of body weight in adult men and 20-25% in women. If this rate rises above 25% in men and 30% in women, the result is obesity and is defined in terms of BMI (Body Mass Index). The World Health Organization (WHO) defines obesity as “excessive fat accumulation in the body to the extent that it impairs health.” Obesity surgery refers to all of the surgical approaches, which can also be defined as stomach reduction, that contain various protocols before and after surgery and that differ according to the needs of the patient.