Gastric bypass surgery makes the stomach smaller and causes food to bypass part of the small intestine. You will feel full more quickly than when your stomach was its original size. This reduces the amount of food you can eat at one time. Bypassing part of the intestine reduces how much food and nutrients are absorbed. This leads to weight loss.
One type of gastric bypass surgery is a Roux-en-Y gastric bypass.
In normal digestion, food passes through the stomach and enters the small intestine, where most of the nutrients and calories are absorbed. It then passes into the large intestine (colon), and the remaining waste is eventually excreted.
In a Roux-en-Y gastric bypass, only a small part of the stomach is used to create a new stomach pouch, roughly the size of an egg. The smaller stomach is connected directly to the middle portion of the small intestine (jejunum), bypassing the rest of the stomach and the upper portion of the small intestine (duodenum).
This procedure is done by making several small incisions and using small instruments and a camera to guide the surgery (laparoscopic approach).
What To Expect After Surgery
You will have some belly pain and may need pain medicine for the first week or so after surgery. The cut that the doctor makes (incision) may be tender and sore. Because the surgery makes your stomach smaller, you will get full more quickly when you eat. Food also may empty into the small intestine too quickly and lead to dumping syndrome. This can cause diarrhea and make you feel faint, shaky, and nauseated. It also can make it hard for your body to get enough nutrition.
Your doctor will give you specific instructions about what to eat after the surgery. For about the first month after surgery, your stomach can only handle small amounts of soft foods and liquids while you are healing. It is important to try to sip water throughout the day to avoid becoming dehydrated. You may notice that your bowel movements are not regular right after your surgery. This is common. Try to avoid constipation and straining with bowel movements.
Bit by bit, you will be able to add solid foods back into your diet. You must be careful to chew food well and to stop eating when you feel full. This can take some getting used to, because you will feel full after eating much less food than you are used to eating. If you do not chew your food well or do not stop eating soon enough, you may feel discomfort or nausea and may sometimes vomit. If you drink a lot of high-calorie liquid such as soda or fruit juice, you may not lose weight. If you continually overeat, the stomach may stretch. If your stomach stretches, you will not benefit from your surgery.
In a gastric bypass, the part of the intestine where many minerals and vitamins are most easily absorbed is bypassed. Because of this, you may have a deficiency in iron, calcium, magnesium, or vitamins. This can lead to long-term problems, such as osteoporosis. To prevent vitamin and mineral deficiencies, you may need to work with a dietitian to plan meals. And you may need to take extra vitamin B12.
Depending on how the surgery was done (open or laparoscopic), you'll have to watch your activity during recovery. If you had open surgery, it is important to avoid heavy lifting or strenuous exercise while you are recovering so that your belly can heal. In this case, you will probably be able to return to work or your normal routine in 4 to 6 weeks. The surgery is most commonly done as a laparoscopic procedure, which means the recovery time is faster.
Why It Is Done
Surgery is generally considered when your body mass index (BMI) is 40 or higher. Surgery may also be an option when your BMI is 35 or higher and you have a life-threatening or disabling problem that is related to your weight, such as type 2 diabetes that is difficult to control with diet, exercise, and medicine.
It is important to think of this surgery as a tool to help you lose weight. It is not an instant fix. You will still need to eat a healthy diet and get regular exercise. This will help you reach your weight goal and avoid regaining the weight you lose.
How Well It Works
On average, people lose more than half of their excess weight following Roux-en-Y surgery. Ten years after weight-loss surgery, many people have gained 20% to 25% of the weight they lost. The long-term success is highest in people who are realistic about how much weight will be lost and who keep appointments with a medical team, follow the recommended eating plan, and are physically active.1
Risks common to all surgeries for weight loss include an infection in the incision, a leak from the stomach into the abdominal cavity or where the intestine is connected (resulting in an infection called peritonitis), and a blood clot in the legs (deep vein thrombosis, or DVT) or lung (pulmonary embolism). Some people develop gallstones or a nutritional deficiency condition such as anemia or osteoporosis.
Other risks from Roux-en-Y gastric bypass include:
- Stomach pouch problems. You may need a repeat surgery to repair the stomach and/or the opening between the stomach and the intestine.
- Vomiting. If you eat more than your stomach can hold, you may vomit.
- Hernia. These can be related to the incisions that the surgeon makes or caused by the intestine twisting around itself.
- Kidney stones. Drinking enough water can help.
- Gallstones. Sometimes the gallbladder is removed as part of the surgery. But if your gallbladder is not removed, then you may need to take medicine to prevent gallstones.
What To Think About
Weight-loss surgery does not remove fatty tissue. It is not cosmetic surgery.
Complete the surgery information form (PDF) to help you prepare for this surgery.
Heber D, et al. (2010). Endocrine and nutritional management of the post-bariatric surgery patient: An Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism, 95(11): 4823–4843. Available online: http://www.endo-society.org/guidelines/final/upload/FINAL-Standalone-Post-Bariatric-Surgery-Guideline-Color.pdf.
Adams TD, et al. (2007). Long-term mortality after gastric bypass surgery. New England Journal of Medicine, 357(8): 753–761.
Other Works Consulted
Colquitt JL, et al. (2009) Surgery for Obesity. Cochrane Database of Systematic Reviews (2).