The fundamental principles are eating adequate protein and limited carbs. The evolution of the books gives you a choice of approach: The first book has you calculate protein requirements and count carbs. The second book gives you a table for protein and you count carbs, and the third book goes entirely by portion sizes. There are complexities to the diet once you get into it, but the authors make it clear that it’s fine to just do the minimum.
Michael R. Eades, M.D., and Mary Dan Eades, M.D. (husband and wife)
Carbohydrate of any origin. In the main part of the diet, people eat either 7-10 grams ECC per meal or snack, or “2 small portions,” depending upon the book. Dieters are encouraged to use their carb allotment to obtain maximum nutrition and given guidelines for achieving this. Glycemic index or load are ignored in favor of total amount of carbohydrate and its nutritional content.
Amount of Restriction:
A fair amount of restriction, but not as extreme as the first phases of some other diets. You can "move up a level" if it turns out you aren't doing well on the amount of carbs allowed on Intervention.
Amount of Structure:
Protein and carbs should be spread fairly evenly between three meals and a snack (the snack can be further divided if desired, and is optional).
There is individual variation in protein requirement, but otherwise everyone basically does the same thing until nearing target weight or resolution of health concerns. At that point, ultimate carb level is determined depending on where weight stabilizes.
The dieter has to learn to either count carbs or learn portions (and portion sizes change at each phase). Beyond that, there is a lot to learn about nutrients, including fats, but that can be an ongoing process.
(There is a slight variation between books; throughout this profile I’m going by The Protein Power Lifeplan): The three phases are Intervention, Transition, and Maintenance. The main difference is the amount of carbohydrate allowed.