Overweight women slowly lose leg strength and power when they age than those considered normal weight, say researchers at The University of New Hampshire.
The study also found that they are at high risk of being disabled and losing independence, contradicting the popular image of the bird-thin elder being at greatest risk of becoming disabled due to loss of muscle mass.
Lead author Dain LaRoche, assistant professor of kinesiology at UNH, and two undergraduate students, Rachel Kralian and Erica Millet measured the impact of excess weight on subjects' leg strength, walking speed, and power - the factors that affect activities of daily living like rising from a chair or climbing stairs.
They found very little difference in the absolute strength of the overweight and normal-weight participants.
However, when their strength-to-weight ratio was calculated, the overweight women had an average of 24 percent lower strength than the normal-weight study participants.
The overweight women demonstrated 38 percent less power than the normal weight women.
Walking speed was significantly slower - about 20 percent - for the overweight participants, as well.
"Everything pointed to the fact that it was the extra fat that these people were carrying that was really limiting their mobility," said LaRoche.
"Being of a normal body weight lets you perform activities of daily living and live on your own longer," he added.
Based on the findings, LaRoche suggests that normal-weight adults should work to maintain their weight and strength as they age.
The study has been published recently in the Journal of Electromyography and Kinesiology.