The same way as before!
‘Menopause’ is a natural transition period which may or may not bring physiological changes because of the hormonal changes. Maintaining what we have is getting more difficult as we age, but a large part of it is that we change our habits and often engage less often in physical activity.
Joanne is correct in pointing out the importance of resistance training. The rest – maintaining or building muscles while losing body fat – still is under the same principles as before. Just as some medications impact our metabolism, this transition period may mean for some that a rethinking of the amount of food and exercise is necessary.