If it's food you are going to warm up to eat for dinner, do it within the hour of taking it out, you don't want it to get to room temperature or above. What kind of food are you talking about? Jelly,peanut butter, ketchup,mustard and things like that can be out for  a day or two without the danger of making you ill. Once something is prepared or been in refrigeration, it needs to stay in the refirigerator unless it is to be eaten then or soon because of e-coli or worse.Food poisioning is bad.