Definition & Facts of Weight-loss Surgery

In this section:

What is weight-loss surgery?

Weight-loss surgery encompasses a group of operations that help you lose weight by making changes to your digestive system. It is also known as metabolic and bariatric surgery ("metabolic" means "related to how your body gets energy" and "bariatric" means "related to treatment for heavy weight").

Some types of weight-loss surgery make your stomach smaller, limiting how much you can eat and drink at one time, so you feel full sooner. Other types of weight-loss surgery change your small intestine—the part of your digestive system that absorbs energy and nutrients from foods and beverages. These types of surgery reduce the number of calories the body can absorb. Weight-loss surgery also can affect hormones or bacteria in the gastrointestinal tract in ways that may reduce appetite and hunger and improve how the body metabolizes fat and makes use of insulin.

Who are good candidates for weight-loss surgery?

You may be a good candidate for weight-loss surgery if you are an adult who has obesity and you have not been able to lose your excess weight, or you keep gaining back weight you have lost using other methods such as eating plans, exercise, or medications.

Body Mass Index (BMI) is a measure of obesity used to determine who are good candidates for weight-loss surgery. BMI measures body fat based on weight in relation to height. For people with a BMI of 35 or higher, obesity can be hard to treat with diet and exercise alone, so health care professionals may recommend weight-loss surgery. For people with a BMI of 30-35 who have type 2 diabetes that is difficult to control with medications and lifestyle changes, weight-loss surgery may be considered as a treatment option.

Calculate your BMI to learn whether you have obesity.

Graphic shows body mass index rates of 18.5-24.9 as normal, 25-29.9 as overweight, 30-39.9 as obese, and 40 or greater as severely obese.The BMI scale measures body fat based on weight in relation to height.

Weight-loss surgery also may be an option to consider if you have serious health problems related to obesity, such as type 2 diabetes or sleep apnea. Weight-loss surgery can improve many of the medical conditions linked to obesity, especially type 2 diabetes.1,2

Does weight-loss surgery always work?

Studies show that many people who have weight-loss surgery lose on average 15 to 30 percent of their starting weight, depending on the type of surgery they have.3 However, no method, including surgery, is sure to produce and maintain weight loss. Some people who have weight-loss surgery may not lose as much as they hoped. Over time, some people regain a portion of the weight they lost. The amount of weight people regain may vary. Factors that affect weight regain may include a person’s weight before surgery, the type of operation, and adherence to changes in exercise and eating.

Weight-loss surgery can make it easier for you to eat fewer calories and be more physically active. Choosing healthy foods and beverages before and after the surgery may help you lose more weight and keep it off over the long term. Regular physical activity after surgery also helps keep the weight off. To improve your health, you must commit to a lifetime of healthy lifestyle habits and follow the advice of your health care professionals.

How much does weight-loss surgery cost?

Weight-loss surgery can cost between $15,000 and $25,000 or even more, depending on what type of surgery you have and whether you have surgery-related complications.4 Costs may be higher or lower depending on where you live. The amount your medical insurance will pay varies by state and insurance provider.

Medicare and some Medicaid programs may cover the major types of weight-loss surgery if you have a health care professional’s recommendation and you meet certain criteria (for example, if you have a BMI of 35 or greater and obesity-related health problems). Some insurance plans may require you to use approved surgeons and facilities. Some insurers also require you to show that you were unable to lose weight by completing a nonsurgical weight-loss program or that you meet other requirements.

Your health insurance company or your regional Medicare or Medicaid office will have more information about weight-loss surgery coverage, options, and requirements.


Last Reviewed September 2020
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by NIDDK is carefully reviewed by NIDDK scientists and other experts.