Not all of us can afford the luxury of fresh and hot food right at the time of having meals. I am saying this because we all are tied up for time and mostly need to cook in the morning or evening as per our convenience.
So we either take packed lunches to work or have to reheat it when back home. Defrost the food completely before reheating it in a microwave oven. This will require less power too. It is best to eat food while fresh as it is rich in nutrients that are lost on heating again and again.