Understanding Bariatric Surgery and Lasting Weight Loss
Clear, research-grounded information about weight-loss surgery — who it helps, what the procedures involve, and what long-term outcomes look like — together with a preserved archive of the landmark LABS study materials.
About bariatric surgery
Bariatric surgery — including gastric bypass, sleeve gastrectomy, and adjustable gastric banding — is the most effective long-term treatment for severe obesity. Beyond weight loss, it can improve or resolve type 2 diabetes, hypertension, sleep apnea, and other obesity-related conditions.
Who qualifies
Surgery is generally considered for adults with a BMI of 40 or higher, or 35 or higher with serious obesity-related health conditions, after other weight-loss approaches have not worked.
Common procedures
Roux-en-Y gastric bypass and sleeve gastrectomy are the most performed operations in the United States today; adjustable gastric banding was widely used in the 2000s and studied extensively.
Long-term outcomes
Large prospective studies show durable weight loss and improved health for most patients years after surgery, alongside real risks that require informed, careful decision-making with a surgical team.
About the LABS study
The Longitudinal Assessment of Bariatric Surgery (LABS) was a large, NIDDK-funded prospective cohort study conducted at six clinical centers across the United States. It followed adults undergoing bariatric surgery to measure safety, weight change, and health outcomes over time, with its findings published in JAMA and other leading journals.
This site preserves selected materials from the LABS study participant website — study news, results summaries, and participant resources — recovered from the Internet Archive. They are historical documents, kept here for reference.
Explore the site
BMI Calculator
Calculate your body mass index in US or metric units and see the standard weight categories.
LABS study archive
Restored pages from the participant website: study news, results, fact sheets, and more.
Frequently asked questions
What is bariatric surgery?
Bariatric surgery is a group of operations — including Roux-en-Y gastric bypass, sleeve gastrectomy, and adjustable gastric banding — that change the digestive system to support substantial, lasting weight loss. It is the most effective long-term treatment for severe obesity and can improve or resolve related conditions such as type 2 diabetes, hypertension, and sleep apnea.
Who qualifies for weight-loss surgery?
Surgery is generally considered for adults with a BMI of 40 or higher, or a BMI of 35 or higher together with a serious obesity-related health condition, after non-surgical approaches have not worked. You can estimate your BMI with our BMI calculator, but eligibility is always determined by a qualified bariatric team.
What was the LABS study?
The Longitudinal Assessment of Bariatric Surgery (LABS) was a large NIDDK-funded prospective cohort study that enrolled 2,458 adults who underwent 2,686 bariatric procedures at six U.S. clinical centers, with follow-up of up to seven years. Selected materials from its participant website are preserved in our LABS study archive.
Is this site affiliated with the NIH or NIDDK?
No. niddklabs.org is an independent informational resource and is not affiliated with, endorsed by, or connected to the NIH, NIDDK, or the LABS research group. See About this site for details.
Is the information here medical advice?
No. Nothing on this site is medical advice. Decisions about bariatric surgery — including whether you are a candidate and which procedure fits your situation — should be made together with a qualified surgical and medical team.