I only bring this up because it absolutely amazes me how much food is wasted (or at least unnecessary) when I go out to eat. We almost never waste food when we eat at home, and I hate paying for food that I don’t eat, especially when I know people are starving in other countries (I can hear my mother saying it right now). Many times I overeat when I go out because I loathe paying for stuff I don’t use.
How about the marvelous invention called the doggie bag? If you can truly deal with portions 1/3 or 1/2 the size, that says to me that if you brought the excess home with you, you could have leftovers the next night, or at least for lunch the next day. The way I see it, when I go out to Outback Steakhouse or TGI Fridays, I expect to take something home. If people actually throw out 2/3 or 1/2 of their meal, then I don't blame the restaurant, I blame the customer for not being sensible enough to bring the food home.