A new report finds that older women have a harder time replacing lost muscle than men of the same age. One reason, says co-author and Washington University School of Medicine associate professor Bettina Mittendorfer, is how they process food. "Food intake, particularly protein in the food, is really the major stimulus of muscle protein synthesis." Mittendorfer adds that the response to feeding is much less in older women. "So they increase the rate of muscle protein synthesis to much less of a degree than men do."

Subjects in the study fasted overnight and were later given protein drinks that could be detected in their muscle tissue. The study revealed that older women did not ingest as much dietary protein as similarly aged men in the study.

Mittendorfer attributes the difference to the hormonal changes triggered by female menopause. "In young individuals there doesn't seem to be any difference between men and women. Only as they get older, and so that's why we think it is the menopause, likely the [loss of] estrogen with menopause that is responsible for the deficit in older age."

Mittendorfer says researchers next plan to study whether adjusting amounts of dietary protein helps prevent muscle loss. "We'll actually look at men and women and also focus on women in particular with regards to dose-response relationships that have been described in men before, but there is no such knowledge about the women. We think with more you would get a better response, but it is not really known yet."

After age 50 people lose up to .4 percent of muscle mass a year making, them more prone to fractures and falls. Mittendorfer says the study underscores the need for older women to eat plenty of protein such as eggs, fish, chicken and lean red meat, in conjunction with exercise, to strengthen muscles over time.

The study was published in the Public Library of Science One