I am always kind of skeptical when someone says there is a sure fire, easy way to lose weight, and this book is no exception. In many ways, the information presented in the book does make a lot of sense, and is similar to other diet plans on the market, eliminating gluten, corn, processed sugar, things like that. As someone who is gluten intolerant, I have become much more open minded about the idea that certain foods we would think would be good for us simply are not. So, in that aspect, the information in the book makes a modicum of sense.
However, the concept that calories do not matter at all, and the concept of substantially larger portions for people who need to lose much more weight seem to contradict everything I have ever learned from any doctor or nutritionist. Personally, I do not think I would be able to follow this plan. There is a lot of frequent change in the types of foods you can and cannot eat, and I can imagine it would lead to higher grocery bills and a lot of wasted food, even if you do freeze a lot of your leftovers. It seems really complicated to me, and I am not sure losing 20 pounds in 28 days is even a healthy goal in the first place.
If you are looking for a dietary plan, go talk to a doctor, a health coach, and a nutritionist to make an informed decision. Do not just follow what is fashionable on a television show or in a self help book.