Exercise with diet improves insulin sensitivity much more than diet alone

Obese older adults can reduce their chance of developing the metabolic syndrome by losing weight through dieting alone, but adding exercise to a weight loss program has even more benefit, a new study finds. The results, to be presented at The Endocrine Society's 94th Annual Meeting in Houston, show that a combination of diet-induced weight loss and frequent exercise almost doubled the improvement in insulin sensitivity compared with dieting alone.

The metabolic syndrome is a cluster of metabolic problems that raise the risk of Type 2 diabetes and heart disease: abdominal obesity as shown by a large waist circumference, disturbed lipids (low HDL or "good" cholesterol and high triglycerides), and (blood sugar). Although it is known that can reduce these risk factors, the most appropriate lifestyle treatment for obesity in has been controversial, said the presenting author, Matthew Bouchonville, MD.

"It was not clear from prior studies in obese elderly adults whether the beneficial effects of diet and exercise are distinct from each other or have additive effects," said Bouchonville, an assistant professor at the University of Mexico Health Sciences Center and the New Mexico Veterans Affairs (VA) Health Care System in Albuquerque.

The researchers investigated the independent and combined effects of diet-induced weight loss and regular exercise in a one-year randomized controlled clinical trial, funded by the National Institute on Aging. They randomly assigned 107 ages 65 and older to one of four groups: weight management using a calorie-restricted diet, exercise (three times a week for 90 minutes each) without dieting, combined dieting with exercise, and controls (no diet or exercise).

The primary outcome analyzed was the degree of change in the index. Insulin sensitivity is the body's ability to successfully clear glucose from the bloodstream and is often impaired in obese people. This index was measured from the oral glucose tolerance test, a blood test for diabetes after the patient drinks a sugary drink.

Other measures obtained included those for the components of the metabolic syndrome as well as C-reactive protein, a measure of inflammation. Research has linked chronic inflammation to diabetes and heart disease.

Ninety-three participants completed the study. In the intention-to-treat analysis of all 107 subjects, the insulin sensitivity index did not improve in the exercise-alone group or the controls. This index did improve on average by 40 percent in the diet group and by 70 percent in the combined diet-exercise group after controlling for relevant covariates, Bouchonville reported.

"This suggests a distinct complementary effect of exercise on diet-induced weight loss," he said.

Weight loss by diet alone also led to improvements in blood pressure and C-reactive protein. Without weight loss, exercise did not result in improvement in these risk factors, Bouchonville said. Other measures that did not improve in the exercise-only group or the controls but did improve in the other two groups included glucose and insulin response to the oral glucose tolerance test (levels of insulin and glucose trended over several time points after the sugar intake), , abdominal visceral (deep belly) fat, triglycerides and adiponectin. Adiponectin is a protein produced in fat cells that improves insulin sensitivity.

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

Screening for diabetes at dental visits using oral blood

Feb 26, 2015

It is estimated that 8.1 million of the 29.1 million Americans living with diabetes are undiagnosed and many who have diabetes have poor glycemic control. Given that each year many Americans visit a dental provider but not ...

CBT, sertraline insufficient in diabetes and depression

Feb 26, 2015

(HealthDay)—For patients with diabetes and depression, improvements in depression are seen with cognitive behavioral therapy (CBT) or sertraline, with a significant advantage for sertraline, but glycemic ...

Early signs in young children predict type 1 diabetes

Feb 26, 2015

New research shows that it is possible to predict the development of type 1 diabetes. By measuring the presence of autoantibodies in the blood, it is possible to detect whether the immune system has begun to break down the ...

Daily menu plan reduces blood sugar significantly

Feb 25, 2015

A large group of people with diabetes who followed a menu plan created by University of Alberta nutrition researchers for just three months significantly reduced their blood sugar levels.

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.