This was the first book I read on the subject of weightloss by combining macro-nutrients in the right percentage. I chose this over The Zone as it seemed more user-friendly, and I was right. The system can be complicated at first, until you get used to it, and the Zones blocks are an additional complication. The authors do a great job at explaining why it is so important to balance the right amounts of carbohydrate, protein and fat, and how to choose wisely. It could very well be the first health/fitness book a person reeds and the reader would not feel overwhelmed, as the information is given in a way that it can be easily understood without any previous experience or background in the field of nutrition. The data is complete but you dont feel you need to be a biochemist to understand it, like in some other health books.The book also offers one week of menus, in different variations: the regular ones, the vegetarian and the fat flush, for those who want a more rapid weight loss. The meal plans are furtherly taylored to your individual needs by establishing which type of 4 (A-D) you fall in, depending on your weight and activity level, and therefore being able to establish the right quantity of each food contained in the daily menus. There is also advice on what to choose when dining out and nutritional info on common commercial products, as well as a food value guide (how much protein is in 4oz of chicken breast?) to help the reader make the right choices and design his menus following the 40-30-30 regimen.Overall, a very good guide, which doesnt get 5 stars just because at an attentive eye (from someone who has a background in nutrition/health/fitness), the plan would be even better if it was lighter on the sodium and dairy, but still, its a great improvement over the current nutrition of most people.I would suggest it to anyone who wants to lose weight but also to anyone who wishes to improve his/her fitness performance and energy levels.