Instruct: Classify Amazon reviews into positive or negative sentiment
Query: This book is based on opinions of the author.

I've read many fasting books and this one was very disappointing. Patricia Bragg offers many opinions non of which are based in the facts I was looking for. The best book I've read so far on fasting is: "Fasting and Eating for Health : A Medical Doctor's Program for Conquering Disease" by Joel Fuhrman and Neal D. Barnard, which offers many medical references.