I imagine that the sentiment started with a scarcity of resources: “you better eat all your dinner because we don’t know when we’ll be able to buy more food.”

Or maybe, out of guilt: “finish your dinner, there are children starving in [insert developing nation here].”

Another likely scenario is an aversion to wastefulness: “you put that food on your plate, now you have to eat it because I’m not throwing it away.”

Especially in this day of Absolutely Ridiculous Portion Sizes in Restaurants, the last one resonates the most with me.  Until I realized this very simple truth:

Waste in, waste out.

Allow me to explain.  “Waste in” means that if I put more food in my body after I am already full, it is a waste.  It is a waste because it will add extra resources that my body does not need and then will be forced to store.  In layman’s terms: weight gain.

“Waste out” is the other side.  If I don’t eat the food, it will be wasted and go directly into the garbage, without being at all useful to anyone.

However, at the point that all possible futures for what is still on your plate constitutes a waste, do you really want it going to your waist?  (sorry ’bout that)

This leaves exactly two ways that the food still on your plate won’t end up being a waste.  You could eat it when you are hungry again.  That may work for some foods and some people, but in all honesty, I’m not a huge fan of leftovers.  Not sure why, because I’m not an insane quality snob or anything, but I’ve just always preferred a good meal the first time around.

The other option, the one I employ as often as possible, is to give your restaurant leftovers to someone who needs a good meal.  When I lived in Berkeley, I you could easily judge the authenticity of a pan-handler’s need by their reaction to offered leftovers.  Of course, in order to pull this one off, you probably have to be living in something like a city and also be walking.  Both of those things are good for you, too, by the way.