Nutrition is one of the most basic requirements of life during the time period between the birth and death of an organism. Human beings have been nourished in a way in order to continue their lives in every period of the history of the humanity. However, not every type of nutrition is balanced nutrition. Daily calorie requirement of an individual to be taken in a balanced diet varies according to the age, gender, mode of living, physiological specifications and presence of an accompanying disease. Energy intake and consumption should be balanced in order to maintain a healthy life.

Obesity, when considered globally, is a critical problem of public health. It is generally defined as an increase in the body weight compared to body height in more than a desired level as a result of an excess increase in the ratio of fat mass to the lean mass of the body. World Health Organization, on the other hand, defines obesity as the accumulation of fat in the body in abnormal amounts that seriously jeopardizes health. In other words, increase in the fat ratio of the body results in obesity, more than 25% of men and 30% of women. Although it has frequently ?been encountered in developed countries, its prevalence is gradually increasing in developing countries as well.

Body Mass Index (BMI), the index formulated by the World Health Organization has been used to determine obesity. BMI greater than 30 is accepted as obesity. However, individuals with a BMI greater than 35 and an uncontrolled accompanying disease and persons with a BMI greater than 40 are candidates for surgery.

It has a complex structure due to its etiology. The disease has genetic, metabolic, hormonal, hypothalamic, physical, psychological and socioeconomic aspects. In addition, industry, urbanization, sedentary lifestyle, consumption of high-calorie fast foods with high sugar and fat contents and eating habits like eating on the run are among the factors that play a significant role in the development of obesity.

Targets of the treatment of this disease that affects all the organs in the body are a loss of an adequate amount of body weight, an adaptation of the habit of adequate and balanced nutrition and improvement of the quality of life of the individual. However, maintaining the low body weight in addition to losing weight is dependent on the change of eating habits in the long run and increased physical activity in these patients.

Treatment of obesity includes the steps of a healthy nutritional diet, exercise treatment, behavioral treatment, pharmacological treatment, and surgery.

Currently by the frequent use of bariatric surgery, weight loss at a rate of 41%-66% and significant improvements in the accompanying diseases are achieved in those patients. At present, surgery is the most efficient method of treatment in light of the current literature. However, preoperative rehabilitation, patient preparation and a careful follow-up of consultations are needed in order to avoid the possible and potentially catastrophic postoperative complications of surgery. Also, it is one of the most important issues to obtain a positive decision by a council composed of experts in endocrinology, general surgery, dieticians, psychiatry and pulmonary diseases in order to avoid medicolegal problems.

In conclusion, obesity is a secretly growing disease that should be evaluated medically. Consequences of untreated obesity may be severe. Operations performed for obesity provide a significant weight loss. Treatment is most efficacious when the steps described above are applied in combination. Pre-and post-surgical rehabilitation is substantially important. In light of this information, we, physicians should always consider obesity as a metabolic disease that plays a fundamental role in many other diseases, not only as a condition that disturbs the physical appearance of an individual.