Clinical Trials for Weight-loss Surgery

The NIDDK conducts and supports clinical trials in many diseases and conditions, including obesity. The trials look to find new ways to prevent, detect, or treat disease and improve quality of life.

What are clinical trials for weight-loss surgery?

Clinical trials—and other types of clinical studies—are part of medical research and involve people like you. When you volunteer to take part in a clinical study, you help doctors and researchers learn more about disease and improve health care for people in the future.

Researchers are studying many aspects of weight-loss surgery, also called metabolic and bariatric surgery, as a treatment for obesity, such as

  • which types of weight-loss surgery might be appropriate for people who have severe obesity (BMI greater than or equal to 40) or lower levels of obesity (BMI less than 35)
  • the effects of weight-loss surgery on conditions that frequently co-occur with obesity, such as diabetes
  • interventions that can help weight-loss surgery patients maintain weight loss over time

Find out if clinical studies are right for you.

Watch a video of NIDDK Director Dr. Griffin P. Rodgers explaining the importance of participating in clinical trials.

What clinical studies for weight-loss surgery are looking for participants?

You can view a filtered list of clinical studies on weight-loss surgery that are federally funded, open, and recruiting at You can expand or narrow the list to include clinical studies from industry, universities, and individuals; however, the National Institutes of Health does not review these studies and cannot ensure they are safe. Always talk with your health care provider before you participate in a clinical study.

What have we learned about weight-loss surgery from NIDDK-funded research?

Longitudinal Assessment of Bariatric Surgery

From 2003 to 2016, the NIDDK partnered with researchers to create the Longitudinal Assessment of Bariatric Surgery, or LABS. The researchers examined the safety and effectiveness of two types of weight-loss surgery in adults, gastric bypass and adjustable gastric band.

LABS found that weight-loss surgery performed by experienced surgeons is relatively safe, leads to significant weight loss, and improves many weight-related health problems. After 7 years, the average weight loss of the gastric bypass patients was 84 pounds, or about 28 percent of their starting weight. The average weight loss of the gastric band patients was 41 pounds, or about 15 percent of their starting weight.12 In a separate analysis, LABS found that gastric band surgery was associated with a small but significant increased risk of problem alcohol use after surgery.13


A separate group of researchers conducted similar research with teens in the severe obesity range and had serious weight-related health problems. This project, called Teen-LABS, found that at 5 years after the operation, patients who had gastric bypass surgery lost between 51 and 64 pounds.14 This represented about 26 percent of their starting weight. The teens also had improved overall health and quality of life. The Teen-LABS study is continuing for several more years, to gain information on the longer-term benefits and risks of weight-loss surgery with teens.


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.