No you get too tired to do anything. You burn yourself out. In extreme cases (ie marathon runners) you "hit the wall"...this means your body is telling you to stop - now! A bit like death is nature's way of telling you to slow down.
Rest has it's place in weight loss as well. In these down times our body is adjusting itself to the new conditions. It is building new muscle and moving your metabolism to a different place to cope with the new demands you are placing on it. Allow this process to happen and you will have successful weight loss. Push the issue; don't listen to your body and you will burn out and end up giving up.