Scientists have discovered that it is more difficult for women to replace muscle as they get older because the way their bodies react to food differs from men.
A study involving postmenopausal women found that they were less able to respond to food to build muscle mass than men of the same age, who were better able to store protein in muscle.
Experts believe that the disparity may be due to hormonal changes that occur during the menopause, particularly as younger men and women do not show the same differences.
The study was conducted by teams at the Washington University School of Medicine and the University of Nottingham.
"Nobody has ever discovered any mechanistic differences between men and women in muscle loss before. This is a significant finding for the maintenance of better health in old age and reducing demands on the National Health Service," said Michael Rennie, professor of clinical physiology at the University of Nottingham.
Professor Rennie suggested that older people should try to eat a higher proportion of protein in order to help reduce the loss of muscle mass over time.
"There is also a case for the beneficial hormonal effect of limited HRT, although this has to be balanced against the other risks associated with such treatment," he noted.