Combining weight loss diet with an exercise program may be more effective for older adults in losing excess weight. Such a regimen also reduces the risk of metabolic syndrome, a new study reveals.
The results of the study show that a combination of diet-induced weight loss and frequent exercise almost doubles 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, high blood pressure and high blood sugar.
Although it is known that weight loss can reduce these risk factors, the most appropriate lifestyle treatment for obesity in older adults has been controversial, presenting author Matthew Bouchonville said.
"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," Bouchonville, from the University of Mexico Health Sciences Center and the New Mexico Veterans Affairs (VA) Health Care System in Albuquerque, said.
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 obese adults aged 65 and older to one of four groups - weight management using a calorie-restricted diet, exercise without dieting, combined dieting with exercise, and controls.
The primary outcome analyzed was the degree of change in the insulin sensitivity 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.
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, waist circumference, deep belly fat, triglycerides and adiponectin.
Adiponectin is a protein produced in fat cells that improves insulin sensitivity.
The findings of the study will be presented on Saturday at The Endocrine Society's 94th Annual Meeting in Houston.