Food retained over time is prevented from looking stale when kept in the refrigerator. But this food has deteriorated in the nutritional content though it looks as colorful and shiny as it was. Food rewarmed from the refrigerator activates growth of contaminating microorganisms. If using the fridge is unavoidable, restrict to keeping foods in the fridge not more than a day and only one rewarming or reuse of the stored food. Repeated storage and use increases the health hazard.
Microwave heats the water and fat molecules in the food from inside. The inner heat damages the micro nutrients, vitamins and minerals in the food. Microwave though appears to be convenient, is best avoided.