I can't help myself, I just have to do it. My kids never eat everything on their plates and I hate waste, or so I tell myself, so I finish their meals. I keep telling myself not to do it and we even have a dog that would love to eat leftovers, but, each time it's gutsy here who does it!
I do the same thing. I once had the brilliant idea of not fixing myself a plate and letting my dinner consist of kids' leftovers only. It wasn't such a brilliant idea since it would only whet my appetite and I'd overcompensate on horrid snacks to fill the gap.
The only way I avoid the problem is to close my eyes and let them scrape their scraps into the garbage.
Ruby, have you ever thought about buying and cooking less? I am the same way because I was raised in a "clean your plate" household; now I can't leave food on my plate or leave it alone when hubby leaves food on his. Finally I had to make up for it by cooking less and less so that eventually we didn't even have leftovers anymore.