Longer weight loss treatment programs may be necessary to improve blood sugar levels

Current clinical recommendations for behavioral weight loss treatment call for 16 weekly sessions, but that may not be enough to improve blood sugar levels in patients who are at risk for developing diabetes, University of Florida researchers have found.

The scientists discovered that among people who participated in eight-week, 16-week or 24-week weight loss treatment sessions, only the participants in the 24-week treatment group achieved significant improvements in their hemoglobin A1c (a measure of average blood sugar over two to three months), as well as fasting blood glucose, when compared to a nutrition education control group. The findings appear in the journal BMJ Open Diabetes Research & Care.

“We hope that our findings may help guide physicians in their clinical decision making to help patients achieve not only weight loss, but also meaningful reductions in blood sugar,” said lead author Viviana Bauman, a third-year doctoral student in the College of Public Health and Health Professions’ department of clinical and health psychology.

Organizations such as the American Diabetes Association and the Centers for Disease Control and Prevention recommend that people whose blood sugar levels meet the criteria for prediabetes, a major risk factor for Type 2 diabetes, participate in treatment programs to lose weight and lower blood sugar.

For the current study, researchers analyzed data from the Rural Lifestyle Intervention Treatment Effectiveness, or Rural LITE, trial, led by Michael G. Perri, Ph.D., dean of the College of Public Health and Health Professions and a professor in the department of clinical and health psychology. Participants were assigned to a low dose (eight weeks), moderate dose (16 weeks) or high dose (24 weeks) of a behavioral weight loss intervention. Program content was based on the National Diabetes Prevention Program. Participants met in groups for 90 minutes weekly with an interventionist and were instructed to follow a low-calorie diet, increase physical activity using a home-based walking program and use behavior change strategies, such as goal setting, daily steps and problem-solving techniques. A nutrition education control group (eight weeks) received education on nutrition and physical activity, but no instruction on behavioral strategies.

Bauman and her colleagues analyzed outcomes for the 287 participants in the Rural LITE trial who had blood sugar levels in the prediabetes range. Participants in the high-dose treatment group had a larger, though not significantly greater, weight loss than the moderate-dose treatment (an average of 24 vs. 22 pounds), both of which were significantly greater than the losses in the low-dose and education control conditions (14 and eight pounds, respectively).

Researchers found significant improvements in blood sugar over six months in both the high and moderate dose conditions, but not in the low and control conditions. In addition, compared to the low and control conditions, only the high-dose group experienced a significantly greater improvement in blood sugar levels.

“These findings leave us with some intriguing questions that are yet to be answered,” Perri said. “For example, were the improvements in glycemic control observed for the high   dose group vs. the low and control conditions (but not for the moderate group vs. the low and control conditions) due to the small additional amount of weight loss in the high vs. moderate conditions? Or, could the findings be attributed to the greater length of dieting in the high vs. the moderate conditions?”

Bauman notes that unfortunately, some weight regain among participants is common when weight loss treatment programs end. Scientists should continue to evaluate treatment approaches that offer ongoing support to help people maintain weight loss and healthy behaviors.

“There are still a lot of different approaches being tested for weight loss maintenance and one thing that stands out is continued contact,” she said. “Studies have shown over and over again that when you treat overweight or obesity as a chronic condition versus an acute problem, you are able to sustain weight loss longer term.”

In addition to Bauman and Perri, the study authors include Aviva Ariel-Donges and Eliza Gordon, doctoral students in the UF department of clinical and health psychology; Michael Daniels, Sc.D., professor and chair of the UF department of statistics; Dandan Xu, Ph.D., of the department of statistics and data sciences at the University of Texas at Austin; Kathryn Ross, Ph.D., an assistant professor in the UF department of clinical and health psychology; and Marian Limacher, M.D., a professor of medicine and senior associate dean in the UF College of Medicine. The study was funded by a grant from the National Institutes of Health.