If you've tried diets and exercise programs and you're still struggling with obesity, you may be thinking about weight loss surgery, and wondering about the criteria for being a candidate.
More than 40% of adults in the U.S. have a body mass index (BMI) of more than 30, which meets the definition of obesity. Nearly 10% have severe obesity (BMI of more than 40). Not all people with obesity have other health problems, but they do have a higher risk of developing heart disease, type 2 diabetes, arthritis and some types of cancer. If you are obese, losing significant weight may lower your risk of those diseases or lessen their severity. If you already have type 2 diabetes, losing weight can reduce your need for medications and even reverse the condition.
Who is a good candidate for weight loss surgery?
You may be aware that it can be very difficult for some people with obesity to achieve significant weight loss with diet and exercise alone. Weight loss surgery may be a good choice in these circumstances, especially if you have other health conditions that are made worse by obesity.
According to the National Institute of Diabetes and Digestive and Kidney Diseases, weight loss surgery may be an option  for adults who have:
- Severe obesity (BMI more than 40)
- A BMI of 35 of more and health problems such as type 2 diabetes, heart disease or sleep apnea
- A BMI of 30 or more with type 2 diabetes that doesn't respond to medication or lifestyle changes
People who get weight loss surgery can lose 30% to 75% of their excess body weight, depending on the surgical method and how well they are able to follow diet and exercise recommendations before and after surgery.
In recent years, weight loss surgery has become safer, and studies show that it can improve health and well-being  for many people. But it is not for everyone, and many factors go into deciding whether to try it and which type of weight loss surgery to try. People who undergo weight loss surgery still need to stay active and watch what they eat and drink — in fact, they may have to be more careful than ever.
Types of weight loss surgery
There are several types of weight loss surgery, and each has different risks and benefits to consider.
Gastric bypass surgery
In gastric bypass surgery, the surgeon creates a small pouch with the top of the stomach and attaches it to the small intestine. The new smaller stomach helps you feel full faster, and, since food passes through only part of the digestive system, the body absorbs fewer calories and nutrients. The surgery also results in changes in appetite and how the body breaks down food.
This surgery is usually done through a small incision with a laparoscope, which is a long, thin instrument. The procedure is more complex than some others, and patients have a higher risk of complications and nutrient deficiencies afterwards. However, it has a high rate of successful weight loss. On average, people lose about two-thirds to three-quarters of their excess weight.
In a sleeve gastrectomy, the surgeon removes 80% of the stomach, specifically the part of the stomach that produces the hormones that make you feel hungry. After surgery, people feel less hungry and feel full faster. It is a simpler procedure than gastric bypass that has fewer complications and a faster recovery time. However, some people may experience reflux or heartburn. Weight loss tends to be a bit lower than it would be with gastric bypass surgery.
In a third type of weight loss surgery, the surgeon uses an adjustable gastric band to create a small pouch at the top of the stomach but makes no changes to the intestines. The band is adjustable and can be removed, if necessary. It is the simplest of the three procedures and has the lowest risk of nutrient deficiencies, but it also has a lower success rate.
Another type of weight loss surgery is the duodenal switch. This actually involves two procedures: one similar to the sleeve gastrectomy procedure and a second that divides the small intestine into two passages. This surgery is associated with the greatest weight loss, but also the greatest number of complications.
Other considerations for weight loss surgery
In addition to looking at your health profile and the potential risk and benefits of the surgical procedure, there are a few other important aspects of this decision to consider. Health insurance companies have different guidelines about which types of weight loss surgery  they'll cover and under what circumstances. Some policies may require patients to try a weight management program and see a behavioral health provider before approving weight loss surgery.
Choosing weight loss surgery is not an easy answer or a magic bullet. It involves making a commitment to lifelong changes in eating and physical activity patterns. If you feel weight loss surgery is the right choice for you and you are ready to commit to this option, ask your doctor what is the right form of weight loss surgery for you.