Surgical treatment for obesity began in 1956 with the introduction of the jejunum-ileal diversion by Payne and DeWind, where a connection was made between the first part of the small intestine (jejunum) and the last part of the small intestine (ileum), causing mal absorption of nutrients because 90% of the small intestine is excluded. At the beginning this procedure was successful, but it had to be stopped due to the severe side effects such as liver cirrhosis caused by the calories and protein mal absorption, onset of kidney stones, osteoporosis, and severe deficiencies of iron, vitamin B12, A, D, E and K.

Today other Bariatric techniques have been developed all of which have their specific indications, mechanisms of action, results, and complications.

The surgical procedures performed for obesity are divided in several groups:

• Restrictive: consists in reducing or restricting the stomach capacity in order to have a faster sensation of fullness.
• Mal absorptive: consists in the reconstruction of the digestive system where the intestines are reattached in a different place preventing the food that is ingested from traveling through the entire digestive system, therefore the nutrients are not well absorbed.
• Mixed procedures: consists of a procedure that includes some restriction and some mal absorption.
• Procedures that modify the secretion of gastrointestinal hormones.

Different types of Bariatric Surgery: