Great weight loss – or from surgery as a diet – has the same metabolic benefits

Gastric bypass surgery is the most effective therapy for treating or reversing type 2 diabetes in severely obese patients. Many achieve remission of diabetes after surgery and no longer require medication for diabetes. This observation has led to the theory that gastric bypass surgery has unique, weight-loss-independent effects in the treatment of diabetes, but this has remained a long-standing question in the field. Now, new research from the Washington University School of Medicine in St. Louis Louis indicates that weight loss after surgery, instead of the surgery itself, drives metabolic improvements, such as the remission of diabetes.

The researchers studied severely obese patients with diabetes who underwent gastric bypass surgery and then lost 18% of their body weight. For example, in a patient weighing 250 pounds, that would be 45 pounds. The researchers compared those patients with others who were also severely obese with diabetes but had lost the same percentage of body weight only through diet.

After achieving their weight loss goals, members of both groups experienced similar improvements in metabolism – such as lower blood sugar levels throughout the day, better insulin action in the liver, muscle and adipose tissue, and reduction in the need for insulin and other diabetes medications. Since the group that lost weight through diet only did exactly what the surgery group did, the researchers concluded that the improvements were due to weight loss alone, rather than due to physiological changes resulting from the surgery itself.

The study will be published Aug. 20 in The New England Journal of Medicine.

“It is believed that gastric bypass surgery has therapeutic, metabolic effects that result in better glucose control and even remission of diabetes above the effects expected from weight loss alone,” said lead researcher Samuel Klein, MD, director of the Washington University’s Center for Human Nutrition. “But we found that gastric bypass surgery improves metabolic function by causing weight loss. There were no differences in the reduction of diabetes medications or in the rate of diabetes forgiveness between surgeons and those who had lost equal amounts of weight alone. by diet. “

More than 40% of adult Americans are obese, and close to one in 10 is severely obese. Each year, more than 250,000 people undergo U.S. bariatric surgery to help them lose weight. The gold standard procedure, called Roux-en-Y gastric bypass, has been the most successful operation in terms of total weight loss and long-term maintenance.

In this procedure, surgeons working laparoscopically use part of a patient’s football belly to make a pudding the size of a ping-pong ball directly attached to the thin gut, by rounding much of the upper part of the thin road. In this study, gastric bypass procedures were performed by bariatric surgeons, J. Chris Eagon, MD, an associate professor of surgery, and Shaina R. Eckhouse, MD, an assistant professor of surgery.

Klein’s team compared 11 patients for gastric bypass surgery who had diabetes with 11 others who had diabetes and achieved equivalent weight loss with diet alone. The mean age of patients in the diet group was about 55, while the mean in the surgery group was 49. Those in the surgery group lost an average of 51 pounds, while those in the diet group lost an average of 48 pounds. All study patients claimed that weight loss occurred several weeks before follow-up studies were performed.

Over a 24-hour period, the researchers used sophisticated techniques in a hospital setting to measure the metabolic responses of research subjects. They measure insulin sensitivity in the liver, in adipose tissue and in muscle tissue. They also analyzed the response of insulin-secreting beta cells in the pancreas and blood lipid acid concentrations, all of which contribute to the development of type 2 diabetes.

“It has been suggested that weight loss caused by gastric bypass surgery is different from weight loss caused by a low-calorie diet, based on the fact that certain factors – such as increased bile acid concentrations, decreased distributed amino acid concentrations and changes in the intestinal microbiome – are different. surgery patients and may be responsible for the unique therapeutic effects of gastric bypass surgery, ”Klein said. “We found that all of these factors were actually different after weight loss in surgical patients than in patients who lost weight through diet alone. However, those changes were not associated with physiologically or clinically important metabolic benefits.”

According to Klein, also the William H. Danforth Professor of Medicine and Nutrition and Head of the Department of Geriatrics and Nutrition, the loss of weight is the reason for improvements in metabolic function and reversal of diabetes. Weight loss through diet produces the same beneficial metabolic effects as weight loss after surgery.

In an editorial in the paper on the paper, researchers from Tufts University, Harvard University, Massachusetts General Hospital and the University of Maine write that the study “provides a focused and important message for both clinicians and patients – reducing the volume of adipose tissue. tissue, by whatever means, will improve blood glucose control in people with type 2 diabetes. “

“Losing 18% of body weight with diet therapy alone is extremely difficult and unrealistic for most people with obesity,” Klein explained. “In contrast, gastric bypass surgery leads to marked and sustained long-term weight loss, making it a potent therapy for people with diabetes.”

Klein’s study focused on the effects of gastric bypass surgery on metabolic function, and did not look at other medical complications associated with obesity.

“Our study does not rule out the possibility that gastric bypass surgery has unique weight-loss-independent effects on significant clinical outcomes such as arthritis, lung function or cancer risk, which were not assessed. But when it comes to metabolic health, gastric bypass surgery is effective because it causes weight loss, ”he said.