Weight Loss Surgery and Dieting Offer Similar Benefits for People With Diabetes

Weight loss achieved either through a low calorie diet or bariatric surgery appears to result in the same metabolic improvements for obese people with type 2 diabetes, according to a new study.

The results, published in the New England Journal of Medicine on August 20, show patients experienced similar metabolic benefits like improved insulin sensitivity, beta-cell function, and 24-hour plasma glucose and insulin profiles over the course of six months, regardless of whether they dieted or had Roux-en-Y gastric bypass surgery.

To conduct the study, researchers from the Washington University School of Medicine evaluated 11 people who underwent Roux-en-Y gastric bypass surgery for weight loss and 11 people who achieved weight loss through diet alone. Both groups experienced a weight loss of about 18%.

"The results of this study will likely be surprising to some, as it's believed that the Roux-en-Y gastric bypass surgery has metabolic impacts on diabetes independent of weight loss,” Hailey Crean, MS, RD, CDCES, a registered dietitian and certified diabetes care and education specialist in Newton, Massachusetts, tells Verywell. Crean was not involved with the study.

Why the Results Are Surprising

While the medical community agrees that weight loss typically offers metabolic improvements for those who are considered obese and managing type 2 diabetes, certain weight loss procedures are thought to offer a unique benefit. 

In medical literature, bariatric surgery, or weight loss surgery that involves changes to the stomach and small intestine, has been shown to be more effective than other medical therapies for treatment of type 2 diabetes. Bariatric surgery that causes the digestive process to bypass certain areas of the gastrointestinal tract, like the Roux-en-Y procedure, has demonstrated higher rates of diabetes remission than interventions that do not bypass any gastrointestinal section.

Weight loss from a calorie-restrictive diet does not involve any bypassing of the gastrointestinal tract. Therefore, researchers wondered if this method of weight loss would offer fewer metabolic benefits than a Roux-en-Y procedure. Although this recent study involved only a small number of people, it suggests the benefits are similar, regardless of how weight loss is achieved.

The Link Between Weight Loss and Improved Health Outcomes

Being considered obese puts you at risk for several health complications, including type 2 diabetes, according to the American Diabetes Association. It also puts you at risk for issues like hypertension, heart disease, and stroke. 

However, that risk can be reversed.

“Even a small amount of weight loss may help reduce the negative effects of obesity,” Brittany Scanniello, RD, a registered dietitian based in Denver, Colorado, tells Verywell. She says that while you may experience rapid weight loss if you undergo gastric bypass surgery or drastically reduce your caloric intake, it is also possible to lose weight at a steady and slower rate and still see positive outcomes. 

Crean agrees, explaining that even a modest weight loss of 5% to 7% can have a meaningful impact on metabolic markers like insulin sensitivity. However, she says that for people with the goal of long-term weight loss, dieting alone is not always the most effective method.

“With regard to weight loss, it's important to focus on an intervention that addresses long-term maintenance," she says. "From my perspective, this includes addressing factors that influenced initial weight gain, weight cycling history, an emotional relationship with food, or barriers to physical activity."