The findings, “Effect of Exercise Type During Intentional Weight Loss on Body Composition in Older Adults with Obesity,” appeared in the November issue of the journal Obesity.
For 18 months, researchers studied 249 adults in their 60s who were overweight or obese. Participants were randomly assigned to one of three protocols: weight loss only, with no exercise regimen; weight loss plus cardio (walking); or weight loss plus resistance training.
Weight loss plus resistance training (in the form of weight machine workouts) resulted in less muscle loss than either weight loss plus walking or weight loss alone, yet fat loss was still significant in the resistance training group. Participants in this group lost about 17 pounds of fat, compared with 16 pounds in walkers and just 10 pounds in nonexercisers.
Muscle mass loss was about 4 pounds from weight loss plus walking compared with about 2 pounds each from weight loss alone and weight loss plus resistance training. Put another way, the percentage of weight loss coming from muscle mass was 20% with weight loss plus walking, 16% with weight loss alone, and 10% with weight loss plus resistance training.
Loss of fat was associated with faster walking speed, while loss of muscle was associated with reduced knee strength.
“A lot of older adults will walk as their exercise of choice,” said Kristen Beavers, assistant professor of health and exercise science at Wake Forest and lead author of the study. “But this research shows that if you’re worried about losing muscle, weight training can be the better option.”