I'm sure if you could ask the Eadeses that question, they'd rather you read PPLP, because it was their publisher who pressured them into making the original PP a 'diet' book. In the second book, PPLP, nutrition is just one facet of the program, hence the "Life Plan" name. I enjoyed reading both, but PP was definitely more informative with respect to diet. If you buy one, I'd recommend getting the other out of the library. They're both worth reading.