This article is from the Running FAQ, by Ozzie Gontang with numerous contributions by others.
"Good" nutrition is not black and white. As we have seen, the body's
requirements are different depending on the phase it is in. While the
building and recovery phases occur somewhat simultaneously the performance
phase stands by itself. For this reason, some foods are beneficial during
one phase but not during another. A good example is the much maligned
twinkie. In the performance phase it is a very quick source of energy and
quite helpful. However, during the building phase it is not necessary and
could be converted to unwanted fat stores. To complicate matters, the
twinkie may help replenish energy stores during the recovery phase however,
complex carbohydrates are probably more beneficial. So, "one man's meat may
be another man's poison."