The combination of diet and exercise is more effective for improving the physical performance of obese people over 65 than either strategy alone, according to a small study in the New England Journal of Medicine.
While the performance scores of the 27 people in the control group rose by just 1%, the improvement was 12% for the 26 people who received dietary intervention, 15% for the 26 assigned to the exercise group, and 21% for the 28 who got both diet and exercise.
"Weight loss plus exercise improved physical function and ameliorated frailty more than either weight loss or exercise alone, although each of those was beneficial," said the team, led by Dr Dennis Villareal of the Washington University School of Medicine in St. Louis.
"It's surprising because weight loss can worsen physical function" in the elderly, he said. "That's why weight loss is not standard treatment for elderly obese. There's no way to induce weight loss without inducing loss of muscle and bone mass. You can lose a lot of fat, but you can't spare the muscle and the bone, and you need muscle for improving strength and function."
The volunteers in the study were mostly older, white, well-educated women. All had only mild-to-moderate frailty. Dieters were prescribed a diet that was 2000 to 3150 kilojoules below that they needed. Food was not supplied to them.
The exercisers worked out for 90 minutes three times a week with aerobic exercises, resistance training and exercises for balance and flexibility. They were evaluated at the 6- and 12-month mark.
"The type of people we recruited had mild to moderate frailty, they were living in the community, and they are at risk for losing their independence and being institutionalized," Villareal said.
After one year with diet and exercise
- Average body weight decreased by 9% versus 10% in the diet group. Average weight did not go down significantly in the control group or the exercise-alone group.
- Peak oxygen consumption increased 17% compared to a 10% rise with diet and 8% with exercise.
- Quality of life survey scores increased 15% versus 14% in the diet group, and 10% in the exercise group.
- Improvement in gait speed was twice that with exercise alone, and exercisers showed more improvement than dieters.
- Bone mineral hip density dropped 1.1 % compared to 2.6% in the diet-only group. It rose 1.5% in the exercise group. The drop in the combination group "is a concern," said Villareal.
The researchers characterised the loss of bone mineral density as "modest" and said higher doses of calcium or more vitamin D might ameliorate those results.
Patients in the diet and exercise group "lost muscle and bone, but they did not decrease their physical function. In fact, they improved their physical function," he said.
One in five adults age 65 and older are obese, and that ratio is expected to increase because of the growing trend toward obesity in the US population.
(Reuters Health, Gene Emery, March 2011)
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