You can do bariatric medicine through either surgery or internal medicine. The surgery route is as gagolden described. As far as internists doing bariatric medicine, they usually run obesity clinics that are multidisciplinary clinics set up with nutritionists, social workers, physical therapists, etc. The physicians role in these clinics is to help to manage the medical complications of morbid obesity including DM, OSA, HTN, GERD, as well as to come up with a weight loss treatment plan and to decide when to refer these patients for bariatric surgery. These physicians will also play a major role in managing post-bariatric surgery patients. In my experience it is the internists and not the surgeons that manage the long-term post-op issues. Sure, the surgeon might see the patient once in a while, but those visits are usually just for post-op checks and to see if the pt needs any further surgery -- the actual medical and nutrition management is run by the internist, at least in all the obesity clinics I know.
