Dieting Beats Exercise for Diabetes Prevention, Combination Is Best

Release Date: August 30, 2011 | By Carl Sherman, Contributing Writer
Research Source: American Journal of Preventive Medicine


  • A combination of dieting and exercise is most effective in reducing type 2 diabetes risk in postmenopausal women, a new study finds.
  • Dieting alone is more effective than exercise alone in promoting weight loss and reducing the risk of type 2 diabetes.
  • Women at risk for diabetes can lose weight and achieve healthier insulin resistance and fasting glucose measures by improving their diet and exercise habits.
  • Receiving advice about diet and exercise in small groups can reduce women’s risk of developing type 2 diabetes and is more practical than individual counseling from a public health standpoint.
Follow us on Facebook

Lifestyle changes that include dieting to lose weight and exercise can help prevent type 2 diabetes, but researchers were uncertain which element contributes more.  A new study suggests that, in postmenopausal women at least, dietary weight loss alone is effective while exercise alone is not effective, and both together are best of all.

“The effects seems to be additive,” said Caitlin Mason, Ph.D., lead study author. “The women who did both diet and exercise together had the greatest weight loss and greatest improvement in insulin and blood sugar control.” In light of the additional benefits of exercise, such as preserving muscle mass during weight loss, “a combined program is the way to go,” said Mason, a postdoctoral fellow in public health sciences at the Fred Hutchinson Cancer Research Center.

For the study, which appears online and in the October issue of the American Journal of Preventive Medicine, 439 inactive, overweight postmenopausal women were randomly assigned to participate in a dietary weight loss program, an aerobic exercise program, or a program that included diet and exercise, or were told not to change their eating or exercise patterns.

Participants received diet and exercise counseling in groups of eight to 15 women, rather than individually.

The researchers estimated the women’s insulin resistance – which reflects how well or poorly the body metabolizes sugar – and their fasting blood sugar, when the study began and after 12 months. Increased insulin resistance and elevated blood sugar are signs that the risk of diabetes is high.

Insulin resistance improved significantly with diet and a bit more in the diet-plus-exercise group, but not with exercise alone, compared to women who made no changes. Exercise alone did improve fasting glucose, but only when it was elevated to begin with.

Women in the diet group lost an average of 8.5 percent of their initial body weight, while those who had diet plus exercise lost more than 10 percent. Improvement in insulin resistance was proportional to the amount of weight lost.

Jill Crandall, M.D., director of the Diabetes Clinical Trials Unit at the Albert Einstein College of Medicine, said she was “most impressed” by the magnitude of weight loss achieved in the study, “but the effect this will have on glucose metabolism or diabetes risk in the long run is a little hard to say from this paper.”

One of the most useful things the study did was to show that “a group-based program could be very effective for weight loss,” added Crandall, who has no affiliation with the study. From a public health perspective, she said, “anything done in the group setting is more feasible.”

She noted that strengthening exercise appears to have greater benefits for insulin resistance than aerobic exercise, and suggested that its inclusion in future studies might be “a desirable feature.”

TERMS OF USE: This story is protected by copyright. When reproducing any material, including interview excerpts, attribution to the Health Behavior News Service, part of the Center for Advancing Health, is required.

#  #  #

For More Information:

Reach the Health Behavior News Service, part of the Center for Advancing Health, at (202) 387-2829 or

American Journal of Preventive Medicine: Contact the editorial office at (858) 534-9340 or

Mason C, et al. Dietary weight-loss and exercise effects on insulin resistance in postmenopausal women. Am J Prev Med 41(6), 2011.

Tags for this article:
Diabetes   Diet and Nutrition   Obesity   Exercise/Physical Activity  

Comments on this article
Please note: CFAH reserves the right to moderate all comments posted to the Health Behavior News Service. Any inappropriate postings will be removed.

Daniel Solomon says
August 30, 2011 at 1:20 PM

Why does this come to a surprise to people? Diet helps to control sugar/glucose intake while exercise controls/regulates the usage of glucose for energy/fuel. Exercise allows the body to utilize stored glucose, decreased insulin cell resistence, and increases metabolic rate. Controlling and reducing carbohydrate intake allows the body to utilize protein and fat as the main sources of energy. You think it would be common sense that the combo would go hand in hand.
The study group would likely of lost a greater percentage of weight, if they eliminated refined, processed grains and just focused on fruits and veges as the primary source of carbohydrates.

Beth Havey RN says
August 30, 2011 at 5:26 PM

Daniel's last comment speaks to the next steps--if diet is significant, then we need to focus on changing the foods that clients buy at the store. I tell my diabetic clients to shop the periphery of the store when they can and to avoid processed grains, sugar and salt. When you have female clients post menopausal who are NOT overweight but have Type 2 diabetes, you know you have to focus on what they are eating.