[Zork]

I believe that men and women are able to grow "x" amount of breast tissue in terms of numbers and sizes of lobules. Once you have grown it, it is for ever and the only way to get rid of it is surgery. Your breast tissue can shrink a lot, depending on your diet and stimulus, if you loose fat you will loose breast size but not breast tissue. I guess that BO or PM diet is a key to stimulate lobule's growth, once you've achieved maximum growth, you can't get more, and the only thing you can do to have more is to go for stem cells injections like women do. I'm not sure HRT given by endocrinologists will allow you to grow more breast tissue than natural way. I believe if you want to keep your breasts in a good shape, it is important to give them daily stimulus to keep your breast tissue active using a breast pump 30 min once daily is sufficient.
I don't pretend this is the truth, I'm just sharing my experience and what I believe.