ST. LOUIS, March 26 (UPI) -- U.S. and British scientists are finding what older women already know -- women have to do more to get less -- at least when retaining muscle.

The study, published in the Public Library of Science One, suggests post-menopausal women were less able than men of the same age to rebuild muscle mass loss due to aging.

Researchers at the Washington University School of Medicine in St. Louis and The University of Nottingham in England say their findings show the female body's response to food and exercise starts to decline in their mid-60s. The change, they say, is probably the result of hormonal changes after menopause.

In general, women are particularly at risk of muscle loss because they tend to have less muscle and more fat than men in early and middle age and so come nearer to the "danger" threshold of frailty earlier. However, resistance training and eating eggs, fish, chicken and lean meat could help.