Weight-loss surgery improves or resolves diseases including type 2 diabetes, heart disease and high blood pressure and can lead to significant and durable weight loss for many people, but the operation has largely been restricted to those with severe obesity, which means about 75 to 100 pounds overweight or a body mass index (BMI) of 35 or higher with an obesity-related disease.

A new study* presented during the American Society for Metabolic and Bariatric Surgery (ASMBS) 2021 Annual Meeting, however, is challenging this traditional criteria for patient selection with a finding that these same health improvement benefits may be achieved by patients with less weight to lose.

Researchers at East Carolina University Brody School of Medicine in Greenville, NC found that patients with BMIs between 30 and 35, considered Class 1 obesity, lost up to 20% of their initial BMIs and were 45% more likely to be in remission of their type 2 diabetes two years after either gastric bypass or sleeve gastrectomy, the two most commonly performed bariatric surgery procedures. Gastric bypass patients were about twice as likely to be in remission from hyperlipidemia than sleeve patients (50% vs. 25%), and the likelihood of remission of high blood pressure after three years was 60% for gastric bypass procedures and 50% for sleeve gastrectomy.

The real-world study included 566 gastric bypass patients and 730 sleeve gastrectomy patients with an average BMI of 33. Both procedures reduce the size of the stomach and decrease hunger. Health outcomes were obtained from an electronic health record database, which includes patients from different institutions throughout the United States.

“This study confirms the effectiveness of bariatric surgery in patients with Class 1 obesity in real-world settings and suggests earlier intervention in patients with less severe disease should be considered,” said study co-author Maria Altieri, MD, a bariatric surgeon at East Carolina University Brody School of Medicine.

Most health insurers still follow guidelines developed by the National Institutes of Health (NIH) in 1991 when bariatric surgery was only performed as an open procedure. These state that weight-loss surgery should be considered for patients who have a BMI > 40, or “in certain instances” in patients with BMIs between 35 and 40 who also have a serious obesity-related condition such as type 2 diabetes or high blood pressure. BMI is a measure of body fat based on a person's weight in relation to their height.

“The evidence continues to mount that people with lower BMIs can benefit from metabolic and bariatric surgery,” said Matthew M. Hutter, MD, MPH, president of the ASMBS and professor of surgery at Harvard Medical School, who was not involved in the study. “This warrants a reevaluation of patient selection criteria so that all those who can benefit, have access to this lifesaving treatment.”

In a position statement released in 2018, the ASMBS revised its recommendation from 2012 and recommended that individuals with a BMI between 30 and 35 be offered bariatric surgery as an option after failure of nonsurgical treatments though it notes that current nonsurgical treatments “are often ineffective at achieving major, long-term weight reduction and resolution of co-morbidities.”

Additionally 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.

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. 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.

An estimated 256,000 bariatric surgeries were performed in 2019, according to the ASMBS, which represents less than 1 percent of the currently eligible surgical population by BMI. Nearly 60% 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. About 18% of procedures were gastric bypass.

The CDC reports 42.4% of adults in the U.S. had obesity in 2017-2018. Another 9.2% had severe obesity. 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.