why does he need to know? not like he would understand anything about juicing or bodybuilding.. all of the docs that go to my gym workout like girls and have little athleticism or idea of what they are doing. the doc yesterday who is a regular at my gym STARTED OUT doing the ab machine lol then did the rowing machine and then walked around the gym socializing. i did meet a doc one time who used to compete in 5K's though, but for the most part they are bookwormy types who belong playing a sport like tennis or golf.
now if you are going into surgery or have something major going on then yes you should definately tell him. if you take bloods and they come out all screwy its a good idea for them to know cause they are gonna think you have kidney issues