News Release

New data challenges reliance on outdated guidelines to block patients with class i obesity from having weight-loss surgery

Meeting Announcement

American Society for Metabolic and Bariatric Surgery

DALLAS – June 7, 2022 – Weight-loss surgery improves or puts into remission type 2 diabetes, reduces heart attacks and stroke and results in significant and durable weight loss, but a new study finds outdated guidelines issued by the National Institutes of Health (NIH) more than 30 years ago may be stopping a large portion of patients with a lower body mass index (BMI), who could otherwise benefit, from having the surgery or even considering it an option. 

In the retrospective study* presented today at the American Society for Metabolic and Bariatric Surgery (ASMBS)Annual Meeting (#ASMBS2022), researchers found little more than 8,100 weight-loss procedures, either laparoscopic sleeve gastrectomy or laparoscopic Roux-en-Y gastric bypass, were performed on patients with BMIs of less than 35 kg/m(class I obesity) between 2015 and 2019. This is about 1% of the more than 760,000 weight-loss surgeries that were performed during that period. Data was obtained from the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) database for the analysis. 

Researchers theorize so few low BMI patients had weight-loss surgery because most U.S. insurers still rely on NIH Guidelines from 1991, which recommend that surgery only be offered to those with a BMI of 35 kg/mor more, rather than newer and recent guidelines, including from the NIH itselfASMBS, and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO), that lower the BMI cut-off to 30 for patients with an obesity-related disease such as type 2 diabetes. 

“The NIH Guidelines from 1991 are outdated and its recommendations do not reflect decades of data regarding the safety and effectiveness of metabolic and bariatric surgery. Nor does it take into consideration the development of laparoscopic procedures that make the surgery less invasive and safer,” said study co-author Theresa Jackson, MD, a general surgeon and bariatric surgery fellow at Kaiser Permanente, South Sacramento, CA. 

In 2016, 45 professional societies, including the American Diabetes Association, issued a joint statement that metabolic surgery should be considered for patients with type 2 diabetes and a BMI 30.0–34.9 if hyperglycemia is inadequately controlled despite optimal treatment with either oral or injectable medications.

“While non-surgical methods may result in weight loss for patients with class I obesity, metabolic or bariatric surgery is the most effective and durable treatment for their diabetes mellitus and other comorbidities,” said lead study author and bariatric surgeon Zhamak Khorgami, MD, Assistant Professor, Dept. of Surgery, School of Community Medicine, University of Oklahoma,Tulsa. “These patients should not be excluded from such an effective treatment.” 

In the study, patients with lower BMIs undergoing weight-loss surgery tended to be older and female, and have higher rates of type 2 diabetes, hyperlipidemia, and gastroesophageal reflux disease (GERD). There were few differences in the health and safety outcomes between lower- and higher-BMI patients and between weight-loss procedures. 

A comparison of 30-day sleeve gastrectomy outcomes found low-BMI patients had significantly shorter initial hospital stays and operative times, and were less likely to have a complication or be readmitted to the hospital within 30 days than higher-BMI patients, who had a higher rate of admission to the intensive care unit (ICU). Gastric bypass patients with lower BMIs had an increased rate of 30-day hospital readmissions and blood transfusions compared to patients with more severe obesity. 

“Most insurers are ignoring the data and still basing coverage decisions for lower BMI patients on something created more than 30 years ago. It’s time for them to catch up so patients can be treated for obesity and related diseases, including type 2 diabetes, earlier in the disease process,” said Shanu Kothari, MD, President, ASMBS, who was not involved in the study. “Insurance companies generally look to guidelines developed by professional societies to help them determine patient eligibility for surgery. We are simply asking them to more strongly consider data after 1991 and bring their coverage decisions up to date.”

In an updated position statement released in 2018, the ASMBS recommended that individuals with a BMI between 30 and 35 be offered bariatric surgery as an option after failure of nonsurgical treatments. It notes that current nonsurgical treatments “are often ineffective at achieving major, long-term weight reduction and resolution of co-morbidities.” 

About Weight-Loss Surgery

Metabolic/bariatric or weight-loss surgery such as gastric bypass and sleeve gastrectomy have been shown to be the most effective and long-lasting treatment for severe obesity. The operations improve or resolve diseases including type 2 diabetes, heart disease and high blood pressure and leads to significant and durable weight loss. Its safety profile is comparable to some of the safest and most commonly performed surgeries in the U.S., including gallbladder surgery, appendectomy and knee replacement. Weight-loss surgery is generally reserved for people with severe obesity, which means about 75 to 100 pounds overweight or having a BMI of 35 or higher with an obesity-related disease. Obesity is linked to early death and more than 40 diseases including type 2 diabetes, hypertension, heart disease, stroke, osteoarthritis and at least 13 different types of cancer.[i],[ii],[iii] According to the ASMBS, less than 1% of those eligible for weight-loss surgery currently have it in any given year -- about 256,000 bariatric surgeries were performed in 2019, the latest estimates available. 


The ASMBS is the largest organization for bariatric surgeons in the nation. It is a non-profit organization that works to advance the art and science of bariatric surgery and is committed to educating medical professionals and the lay public about bariatric surgery as an option for the treatment of severe obesity, as well as the associated risks and benefits. It encourages its members to investigate and discover new advances in bariatric surgery, while maintaining a steady exchange of experiences and ideas that may lead to improved surgical outcomes for patients with severe obesity. For more information, visit

*National trends in usage of bariatric surgery for class I obesity: An analysis of MBSAQIP 

Theresa Jackson1, Bradley Cox2, Gary Grinberg1, Panduranga Yenumula1, Robert Lim2, Geoffrey Chow2, Zhamak Khorgami;2 Kaiser Permanente, South Sacramento1 and University of Oklahoma, Tulsa


[i]The Effectiveness and Risks of Bariatric Surgery: An Updated Systematic Review and Meta-analysis, 2003-2012. Accessed from:

[ii]Steele CB, Thomas CC, Henley SJ, et al. Vital Signs: Trends in Incidence of Cancers Associated with Overweight and Obesity — United States, 2005–2014. MMWR Morb Mortal Wkly Rep 2017;66:1052–1058. DOI:

[iii] Centers for Disease Control and Prevention. (2015) The Health Effects of Overweight and Obesity. Accessed from:

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