You will not be able to recover from intense physical exertion, since the huge processing of the incoming food also needs energy for digestion. The strength for physical exertion will run out, for digestion too. You are working for wear and tear, and the body will fail
Metabolism during sports, on the contrary, is better, substances from food are absorbed better, they are absorbed more fully by the body, without leaving mountains of toxins and waste in the form of undigested food.
Therefore, proper nutrition and sports go hand in hand. There is no point in intensively loading the body and there is nothing to eat, thus reducing calories, the body itself will require what is needed in the right amount.