Playing certain sports increases your muscular fitness, which increases your metabolism. what will likely not increase during such a sport?

In the sport of football (UK) or soccer (US) the muscles within the hand do not develop that much do the reason that the player only uses their feet in the game. However in a sport such as tennis the player doesn't use their feet muscles to play but instead moves with them. In this case, in tennis hand muscles are the ones used and foot muscles are not developed here. This is because tennis uses arm strength. 

If you under eat, your bones will narrow.