Race plays role in regaining weight after gastric bypass surgery

African Americans and Hispanic Americans who have undergone Roux-en-Y gastric bypass (RYGB) are at greater risk to regain weight as compared to Caucasians. To date, no study has addressed the effect of race on weight regain over the long term. Identifying the risk factors for weight regain is an important first step in improving the long-term clinical outcomes of bariatric surgery.

Obesity is a worldwide epidemic that affects one-third of the U.S. population and 107 million children and 603 million adults globally. All-cause mortality increases by 30 percent for every five-point increase in body mass index (BMI) over 25 kg/m2. Of those affected, 8 percent have class III obesity, defined as a BMI greater than or equal to 40 kg/m2. Bariatric surgery is considered the gold standard and most cost-effective management of severe obesity (BMI ? 35 kg/m2 with associated chronic disease or BMI ? 40 kg/m2), especially for those with metabolic comorbidities such as type 2 diabetes (T2D). RYGB has become the second most common type of bariatric surgery performed after the sleeve gastrectomy in the United States since 2013 and worldwide since 2014.

Using a retrospective review of all RYGB cases performed at Boston Medical Center (BMC) from 2004 to 2015, researchers from Boston University School of Medicine (BUSM) were able to examine the effects of race and T2D on weight regain following weight loss surgery among African Americans, Caucasians and Hispanic Americans. They found African Americans had significantly more weight regain than Caucasians while both African American and Hispanic Americans were more likely than Caucasians to have a period of rapid weight gain over time after reaching their lowest weight after surgery.

According to the researchers, the mechanisms for these racial differences in weight regain after RYGB remains unclear. "Racial or ethnic differences in food choices and eating behaviors have long been linked to obesity and cardiovascular disease. However, it is unclear whether there are racial differences in RYGB-mediated changes in appetite hormonal signals, mental health and eating behaviors," explained corresponding author Nawfal W. Istfan, MD, Ph.D., associate professor of medicine at BUSM and attending physician in the Nutrition and Weight Management Center at BMC.

While previous studies have shown that patients with obesity and T2D lose less weight with medical weight-management interventions, this is the first to identify race as a risk factor for weight regain after RYGB emphasizing the need for future research in diverse populations.

These findings appear online in the journal Obesity.