Dr. Berg's book does a good job of explaining the problems faced by those with insulin resistance, a primary cause of weight gain and other health issues as we age. One of his principles is that the best diet and exercise program for an individual is dependent upon their body type, which he breaks into 4 categories. Although I went through his test to determine my body type, I felt the test was inconclusive for me, which largely reduces the usefulness of the book. Also, I found the meal plan to be something I'd have a very hard time adhering to for an extended period. However, there were some concepts I strongly agree with such as the notion of intermittent fasting to reduce insulin resistance. Overall, I felt the book was helpful in identifying the problems we all face, but not necessarily (for me) a practical solution.