The International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) is a federation composed of national associations of bariatric surgeons.
Currently, there are 40 official member associations of IFSO. There are also individual members from countries that thus far have not formed a national association.

IFSO has been mainly a scientific organization, bringing together surgeons and allied health professionals, such as nurse practitioners, dieticians, nutritionists, psychologists, internists and anesthesiologists, involved in the treatment of morbidly obese patients, but in the upcoming years, IFSO will maintain and extend its roll in the challenge of bariatric surgery.