Unless something has really changed about how DoDMERB operates, you needn't worry about physical fitness at this point. I mean, it's great that you're working out, but DoDMERB is there to see if you have a disqualifying medical condition - not if you meet height and weight standards. That comes later.
It's been a long time for me, but typically they'll grant you a conditional acceptance - the condition being that you qualify medically. I don't think they will withhold your acceptance, but rather your acceptance will be contingent on the outcome of your physical.
