Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. If you want to undergo bariatric surgery means there are many surgeries for it. Each surgery have its own side effects and uses. In Roux-en-Y gastric bypass, the surgeon creates a small pouch at the top of the stomach. The pouch is the only part of the stomach that receives food. This greatly limits the amount that you can comfortably eat and drink at one time. A port is then placed under the skin of the abdomen. A tube connects the port to the band. By injecting or removing fluid through the port, the balloon can be inflated or deflated to adjust the size of the band. Gastric banding restricts the amount of food that your stomach can hold, so you feel full sooner, but it doesn t reduce the absorption of calories and nutrients. Dear possible risks following bypass surgery : 1.Low levels of vitamins if you don’t take 2.supplements daily for the rest of your life 3.Low levels of iron and calcium 4.Trouble getting enough protein 5.Dumping syndrome. This can cause nausea, fast heartbeat, abdominal cramping, fainting, and diarrhea after eating. 6.Narrowing of the sites where intestines are joined (stenosis or stricture) 7.Dangerous internal hernia, in which the small intestine can be trapped and blocked 8.Need for additional surgery 9.Failure to lose enough weight 10.Weight regain, if you snack on high-calorie foods and don’t exercise. I think I answered to your question. If you have more questions feel free to ask. Take care.