I have a real downer on food being wasted. I figure that if an organism has been good enough to lay down its own existence in order to support mine, then the very least I can do is behave with a little gratitude.
For me, this means actually eating all the food that I buy.
The alternative is to flush uneaten food down the sink and into the sewers for the benefit of London's many rats, or adding to our land-fill problems. This question of disposal seems to me to be the practical reason to eat all you buy, but the secondary reason is the feel-good factor you get from knowing you've done right by the many other species responsible for keeping you alive.
The British war-time generation knew this very well. Instead of moving toward an Eat All You Can culture, we should be heading for an "Eat All You Buy" culture.
I think I ought to patent that phrase now.