Why do we waste food? One set of reasons is because it is so easy to do it. For most Americans, food is relatively cheap, and we are lazy. More importantly, we serve too much, so there are often leftovers. American portion sizes are much larger, than, for example, French portion sizes. A third, and perhaps the principal reason, is that there is something unsavory, for many people, about leftovers. They can be conceived of as “used” or “psychologically contaminated” food. Portion size and psychological contamination will be the focus of this presentation.