Conclusions and Relevance This systematic review and meta- analysis did not show a significant beneficial or detrimental association of HT with muscle mass .
Importance Hormone therapy ( HT ) has been suggested for protection against age-related muscle weakness in women .
However , the potential for HT-associated health risks necessitates a better underst and ing of the direction and magnitude of the association between HT and health outcomes , such as lean body mass ( LBM ) .
Objective To determine whether HT was associated with reduced LBM loss compared with not receiving HT  among postmenopausal women aged 50 years and older .
Postmenopausal hormone therapy and body composition--a substudy of the estrogen plus progestin trial of the Women's Health Initiative.
BACKGROUND It has been suggested that hormone therapy may help counter undesirable changes in body composition in older women . OBJECTIVE This study was design ed to test whether estrogen plus progestin ( E+P ) therapy favorably affects age-related changes in body composition in postmenopausal women . DESIGN The sub study was composed of 835 women from the estrogen plus progestin trial of the Women 's Health Initiative who were r and omly assigned to receive either  E+P therapy ( n = 437 ) or placebo ( n = 398 ) . The women had a mean age of 63.1 y and , on average , were 13.8 y past menopause . More than 17 % of the participants were from an ethnic minority . No significant differences in baseline body composition ( measured with dual-energy X-ray absorptiometry ) by intervention assignment were observed . RESULTS After 3 y of intervention , the women who received active E+P therapy lost less lean soft tissue mass ( -0.04 kg ) than did the women who received placebo ( -0.44 kg ; P = 0.001 ) . Additionally , the women in the E+P group had less upper-body fat distribution than did the women in the placebo group ( change in ratio of trunk to leg fat mass : -0.025 for the E+P group and 0.004 for the placebo group ; P = 0.003 ) . A sensitivity analysis , which was conducted on the women who took > or = 80 % of the study medication during the intervention period , corroborated the findings from the intent-to-treat analysis . CONCLUSIONS A 3-y E+P intervention significantly reduced both the loss of lean soft tissue mass and the ratio of trunk to leg fat mass  in postmenopausal women . However , the effect sizes were small , and whether these changes in body composition lead to significant health benefits remains to be confirmed
Conclusions and Relevance This systematic review and meta- analysis did not show a significant beneficial or detrimental association of HT with muscle mass .
Importance Hormone therapy ( HT ) has been suggested for protection against age-related muscle weakness in women .
However , the potential for HT-associated health risks necessitates a better underst and ing of the direction and magnitude of the association between HT and health outcomes , such as lean body mass ( LBM ) .
Objective To determine whether HT was associated with reduced LBM loss compared with not receiving HT  among postmenopausal women aged 50 years and older .