My doctor introduced me to the Paleo diet and referred me to The Wheat Belly. It was kindof dry reading at the start, so I continued my research into this lifestyle and when i came across this book on Amazon.ca, I thought 21 days? What do i have to lose? I lost 8 lbs in the first 2 weeks! Mark has great info, exercises, and the 21 day plan is very helpful. The only thing I don't agree with this book is that you only need to exercise moderately 3-4 days a week. I need to lose approx. 80 lbs and when I slowed down on my exercise, so did the weight loss. I refer to this book and his website often and have purchased some of the other Primal Blueprint products. Thank you Mark!