It's not "directed". It simply goes to whatever has the highest energy requirements. If you are sitting still at your desk all day, not moving a muscle, your

It's not "directed". It simply goes to whatever has the highest energy requirements. If you are sitting still at your desk all day, not moving a muscle, your brain has a large energy requirement. So your muscles will waste, your bones will likely become brittle, but the energy coming in will go where it needs to.