August 7, 2018 / 7:50 PM / 2 years ago

Exercise and dieting tied to reduced disability in obese older adults

(Reuters Health) - Obese older adults who increase their exercise may have less fatigue and disability, but they may see an even bigger improvement if they also cut back on calories, a U.S. study suggests.

Researchers randomly assigned 180 obese adults, ages 65 to 79, to do aerobic exercise, either by itself or combined with moderate or severe calorie restriction for 20 weeks. All of the participants were sedentary but generally healthy and had not smoked in the previous year.

During the experiment, they all did supervised treadmill workouts four days a week, gradually increasing from 15- to 30-minute sessions. One-third of the group made no changes to their diets, while the rest were assigned to consume 250 or 600 calories less than they would need each day to maintain their current weight.

“In older adults with obesity, eating even just 250 less calories per day for five months during an aerobic exercise program enhances many of the benefits of doing moderate-intensity aerobic exercise on a regular basis,” said lead study author Barbara Nicklas of Wake Forest School of Medicine in Winston-Salem, North Carolina.

“The health benefits were the same for those who ate 250 less calories per day as those who ate 600 less calories per day,” Nicklas said by email.

Research on the health benefits diet and exercise in obese adults has generally focused on younger people, researchers note in the Journals of Gerontology Series B. Calorie restriction isn’t widely recommended for obese older adults who exercise, however, because of concern about the potential for malnutrition or loss of muscle mass and strength.

For the current study, researchers assessed the combined benefits of exercise and calorie reduction by focusing on so-called cardiorespiratory fitness, or how easily the body supplies oxygen to muscles during sustained workouts. Cardiorespiratory fitness, or exercise capacity, naturally declines with age, but getting regular exercise and maintaining more lean muscle mass can slow the process. Accumulating more fat can speed it up.

To assess cardiorespiratory fitness, researchers measured what’s known as “peak VO2,” the maximum amount of oxygen the body can use in one minute. Compared to treadmill tests before the start of the study, peak VO2 increased almost eight percent by the end of the experiment in the exercise-only group, by almost 14 percent with moderate calorie restriction and by 16 percent with intense calorie restriction.

The experiment was too brief to determine if these were lasting improvements. Another limitation is that not all dieters achieved the prescribed amount of calorie restriction, even though they were given meal plans and prepared lunches and dinners and met with dieticians.

“A strict reduction in calories is difficult to maintain for most people, especially when coupled with an increase in exercise training,” said Jennifer Schrack, a researcher at Johns Hopkins Bloomberg School of Public Health in Baltimore who wasn’t involved in the study.

“Exercise naturally makes people hungrier, which is why exercise alone is often not enough to sustain weight loss,” Schrack said by email.

Still, the results underscore that even moderate calorie restriction - cutting back on perhaps a few slices of bread or one snack a day for most people - would be enough to achieve substantial benefits from exercise, Schrack said.

“The more difficult part for most people is to initiate an exercise regimen and keep it going,” Schrack added. “This requires substantial motivation and lifestyle change.”

The results suggest even elderly obese adults aren’t too old to benefit from getting more exercise and cutting back on calories, said Dr. Dennis Villareal of Baylor College of Medicine in Houston.

And, for the elderly, any resulting reductions in fatigue and disability might help them live independently for longer and delay or avoid admission to a nursing home, Villareal, who wasn’t involved in the study, said by email.

“It is never too late in life to change diet and activity habits in order to improve quality of life,” Villareal said.

SOURCE: The Journals of Gerontology Series B, online July 5, 2018.

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