New study challenges decades-old patient eligibility criteria for weight-loss surgery

November 05, 2019

LAS VEGAS - Nov. 5, 2019 - Weight-loss surgery has long been shown to improve or resolve diabetes, reduce heart attacks and stroke and produce significant weight loss, but the operation has generally been restricted by health insurers to people with severe obesity, which means about 75 to 100 pounds overweight or a body mass index (BMI) of 35 or higher. Now a new study finds these same health benefits can be achieved by patients who are 50 to 70 pounds overweight and that these patients are even more likely to reach a healthy weight, have a higher quality of life and improve or resolve their type 2 diabetes.

The findings* were presented today by researchers from the University of Michigan (U-M) at the 36th American Society for Metabolic and Bariatric Surgery (ASMBS) Annual Meeting at ObesityWeek 2019.

According to registry data, between 2006 and 2018 more than 44,000 patients underwent sleeve gastrectomy in the state of Michigan, including 1,073 patients with a BMI of less than 35, who were more likely to have diabetes (36.7% vs. 30.9%) and hypertension (54.2% vs. 51%). Researchers found that more than one-third (36.3%) of the lower BMI patients reached a healthy weight or a BMI of less than 25 within a year while only about 6 percent of patients with a BMI of 35 or higher (average BMI 46.7) were able to do the same. BMI is a measure of body fat based on a person's weight in relation to their height.

Diabetes had improved so significantly in both BMI groups that nearly 80 percent of patients no longer needed to take oral diabetes medications and almost two-thirds had stopped taking insulin after one year. More than half were able to discontinue medication for hypertension and hyperlipidemia. The lower BMI group had higher psychological well-being scores (77.9 vs. 73.0), body image scores (52.0 vs. 42.6) and satisfaction rates (90.9% vs. 84.6%). Complication rates were comparable between the two groups (6.9% vs 5.2%).

"We hope the study encourages more patients to consider weight-loss surgery earlier in their disease and for more health insurers to recognize the benefits of lowering the current BMI threshold so more people who could benefit from the surgery have access. Insurance coverage is the price of admission for most patients and it is currently serving as a barrier," said lead study author Oliver Varban, MD, director of bariatric surgery at Michigan Medicine, U- M's academic medical center.

Most health insurers still follow guidelines developed by the National Institutes of Health (NIH) nearly 30 years ago when bariatric surgery was performed as an open procedure that state weight-loss surgery can be considered for patients who have a BMI > 40, or "in certain instances" in patients with BMI's between 35 and 40 who also have a serious obesity-related condition such as diabetes or high blood pressure.

In a position statement released in 2018, the ASMBS revised its recommendation from 2012 and urged the consideration of bariatric surgery for individuals with a BMI between 30 and 35. It states that "there is no current justification on grounds of evidence of clinical effectiveness, cost-effectiveness, ethics or equity that this group should be excluded from life-saving treatment." Meanwhile 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.

"It's time for health insurers to revisit their requirements for surgical treatment which are based on these outdated guidelines," said Eric J. DeMaria, MD, President, ASMBS and Professor and Chief, Division of General/Bariatric Surgery, Brody School of Medicine, East Carolina University, Greenville, NC, who was not involved in the study. "Since the guidelines, bariatric surgery has become one of the safest operations in America and a significant amount of scientific evidence has been generated that shows its benefits extend far beyond weight loss."

Metabolic/bariatric surgery has been shown to be the most effective and long-lasting treatment for severe obesity, resulting in significant weight loss and resolution or improvements in diabetes, heart disease, sleep apnea and many other obesity related diseases.[1] The safety profile of laparoscopic bariatric surgery is comparable to some of the safest and most commonly performed surgeries in the U.S., including gallbladder surgery, appendectomy and knee replacement.[2]

An estimated 228,000 bariatric surgeries were performed in 2017, according to the ASMBS, which represents less than 1 percent of the population eligible for surgery based on BMI. Nearly 60 percent were sleeve gastrectomies, an increasingly popular procedure that involves removing most of the stomach and shaping the remainder into a tube or sleeve, restricting the amount of food it can hold.[3]

The CDC reports 93.3 million or 39.8 percent of adults in the U.S. had obesity in 2015-2016.[4] The ASMBS estimates about 24 million have severe obesity, which for adults means a BMI of 35 or more with an obesity-related condition like diabetes or a BMI of 40 or more. Obesity is linked to more than 40 diseases including type 2 diabetes, hypertension, heart disease, stroke, sleep apnea, osteoarthritis and at least 13 different types of cancer.[5,6,7]
About the ASMBS

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


Is it Worth it? Determining the Health Benefits of Sleeve Gastrectomy in Patients with a Body Mass Index Less than 35 kg/m2

Oliver Varban Ann Arbor MI1, Aaron Bonham Ann Arbor MI2, Dana Telem Ann Arbor MI, Nabeel Obeid Chelsea MI2, Amir Ghaferi Ann Arbor MI2, Jonathan Finks Ann Arbor MI2 -- Michigan Medicine1 University of Michigan2

[1] Weiner, R. A., et al. (2010). Indications and principles of metabolic surgery. U.S. National Library of Medicine. 81(4) pp.379-394

[2] Gastric Bypass is as Safe as Commonly Performed Surgeries. Health Essentials. Cleveland Clinic. Nov. 6, 2014. Accessed October 2017



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

[6] 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:

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

American Society for Metabolic and Bariatric Surgery

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