Kinda back on topic (though I believe she likes chocolate also), I personally like the book "Eat Smart, Play Hard" by Liz Applegate.

She's got the academic credentials and the actual athletic experience -- she runs, she bikes, etc. I think the book is very easy to read and understand without needing a science degree. She addresses both omnivores and the vegetarians.

A bio I copied: Liz Applegate, Ph.D., is on the faculty in the nutrition Department at the University of California, Davis. A Fellow of the American College of Sports Medicine, she is a popular lecturer and has been a guest on Good Morning America, CNN, and ESPN. Dr. Applegate is the author of Power Foods and Eat Your Way to a Healthy Heart. She is nutrition editor and columnist for Runner's World magazine and a nutrition consultant for the U.S. Olympic Team.