Oh no! You have to try to go forward not back word.
Ha. Well, I think essentially you need to eat an amount that is comparable to the amount you exert. When I ate one meal a day, that was fine because I did a bare minimum of physical exercise.
This is why modern society is getting so fat... because exertion reduces (as technology and creature comforts pervade) and intake either remains stagnant or increases (as eating is increasingly regarded as a source of luxurious pleasure rather than of sustenance).
The notion of three meals a day is so unquestioned in modern society, yet there's no way in my mind that most people do enough activity to warrant the calorific intake that comes with three full meals, nevermind the snacks inbetween them.