This is wrong. While there are fundamental metabolic pathways that are the same in all people, I agree in that with Kent, there is a myriad of anecdotal evidence in this forum about individual differences to the same supplements and diets, and there are hundreds of scientific articles showing genetic differences in how effective certain enzymes are, resulting in different metabolic rates of various kinds - e.g. in how well we digest carbs versus proteins versus fats, and how that might affect our cholesterol etc. levels. We don't know how these genetic differences play out, but there are differences, no doubt! Other issues that play a proven role are food allergies, fitness levels etc. I haven't read the book about metabolic typing, so I can't judge whether that is useful - but the idea to consider individual differences in diet and exercise programs is not a bad one that can be discarded as a whole.