The information was good. The book was extremely repetitive though. It may have been written so that each chapter could be read independently.
I have been looking for information about fasting for both nutritional and spiritual benefits and this book covered both topics. Because this book was written 10 years ago, some of the science was a bit dated, but overall it seemed to cover the basics. This author recommends short (1-3 day) juice fasts several times a year, and I have seen and read other publications that suggest the same thing (including the movie Fat, Sick, and Nearly Dead, which is about extended juice fasting).
As far as the spiritual side, Dr Colbert covered some of the major Biblical leaders and type of fasting they used (full, partial, etc) and the results of their choices.
In this book, and the one I read previously (Fasting by Jentezen Franklin), both authors made a similar statement that often in Scripture we find the phrase prayer and fasting, or giving, prayer, and fasting. We talk about praying. We talking about giving (and tithing), but rarely do I hear a sermon on fasting. I do believe it is an important component of worship.
Overall, I'd recommend the book, especially to people looking for some nutritional information about how our diets of processed and artificial foods affect our bodies. I would also recommend the spiritual section to people wanting to learn more about biblical fasting and what that can look like.