Obesity is a disease. Many people with obesity can’t simply lose weight with healthy eating and physical activity, despite how hard they may try. Bariatric (obesity) surgery is performed to treat people who have morbid obesity. Currently, the indications for bariatric surgery are a body mass index of 35 or more with complications from the weight gain, or 40 or more with or without complications.
Bariatric surgery is usually reserved for those who have not responded to nutrition, physical activity, and other non-surgical means of weight loss. Bariatric surgery works by limiting the amount of food you can eat and making your brain register that you are full faster, and/or by limiting the absorption of calories and nutrients from food.
What are the Benefits of Bariatric Surgery?
In addition to weight loss, bariatric surgery may improve diabetes, cholesterol levels, high blood pressure, sleep apnea, and osteoarthritis, among other conditions. Bariatric surgery may also improve fertility in women, especially those with polycystic ovary syndrome, and may increase testosterone levels in men.
What are the Risks of Bariatric Surgery?
The benefits of bariatric surgery must be weighed against its potential risks. In addition to the risks of the surgery itself (such as death, bleeding, infection, and blood clots), bariatric surgery may cause nutritional deficiencies in protein, vitamins and minerals. Bone mineral density loss may develop from inadequate intestinal calcium absorption. Low blood glucose levels (hypoglycemia) after eating carbohydrates, and inadequate vitamin B-12 absorption causing nerve damage to the feet, legs, or hands (peripheral neuropathy), may occur over time.
Bariatric surgery should not be considered in a person who has health conditions that make surgery risky, has certain stomach or intestinal disorders, takes aspirin frequently, or is addicted to alcohol or drugs.
How Bariatric Surgery Works
There are four types of bariatric surgery and each work in different ways to achieve weight loss.
Gastric bypass is the most common bariatric surgery performed in the United States and involves creating a small pouch at the top of the stomach that is attached to a section of the small intestine, thereby “bypassing” most of the stomach and a large section of the small intestine (where calories and nutrients are absorbed).
This stomach pouch restricts food intake and makes you feel full sooner. It also changes the chemical messages sent by the stomach and small intestine (via hormones) to the brain about how much food you have eaten, making your brain register that it is full faster.
Gastric banding involves placement of an adjustable band around the top part of the stomach, creating a small pouch above the band. The tightness of the band opening controls passage of food between the two parts of the stomach, and helps patients feel full faster after eating. Gastric banding does not affect the absorption of calories or nutrients, making it important to follow a strict meal plan after having this surgery in order to achieve weight loss.
This procedure is approved for people with a BMI of 40 or more, or people with a BMI of 30 to 40, who also have an obesity-related health condition, such as high blood pressure, heart disease, diabetes, or sleep apnea.
Duodenal switch involves removal of more than half of the stomach, giving the stomach a tube-like shape and limiting the amount of food you can eat. The stomach remains attached to the first part of the small intestine (the duodenum), but then is split off and reconnected at the lowest part of the small intestine. More of the small intestine is bypassed with this procedure than with a gastric bypass.
Like the duodenal switch, sleeve gastrectomy involves removal of more than half of the stomach to create the shape of a tube, or “sleeve” that limits the amount of food you can eat. Absorption of calories and nutrients is not altered in this surgery.
Bariatric Surgery for Diabetes
In addition to the benefit of feeling fuller faster, bariatric surgery also helps insulin work better to balance the oncoming increase in blood sugar from the food. For a person with obesity and type 2 diabetes, whose pancreas cannot meet the demand imposed by excess weight, bariatric surgery lowers the amount of diabetes medication needed to control blood sugar levels.
Blood sugar levels may begin to improve immediately following surgery and even before the patient begins to lose weight, suggesting that the improvement in blood sugar occurs from both decreased caloric intake in the short term, and from weight loss over time.
As with all surgeries, the benefits of bariatric surgery in the treatment of type 2 diabetes must be weighed against the risk for adverse events from the procedure.
Hormone Health Network®. Endocrine and Nutritional Management After Bariatric Surgery. A Patient's Guide. November 2010. http://www.hormone.org/patient-guides/2010/bariatric-surgery. Accessed March 13, 2014.
American Society for Metabolic and Bariatric Surgery. Benefits of Bariatric Surgery. http://asmbs.org/benefits-of-bariatric-surgery/. Accessed March 13, 2014.
Weight-control Information Network. National Institute of Diabetes and Digestive and Kidney Diseases. Bariatric Surgery for Severe Obesity. NIH Publication No. 08–4006. June 2011. http://win.niddk.nih.gov/publications/gastric.htm. Accessed March 13, 2014.