This isn't a new concept. There are several "low GI" diets. South Beach, Atkins, Sugar Busters, Zone, just to name a few. They are all lower GI than the USDA dietary recommendations, but to varying degrees. Atkins is extremely low. I have been very successful in improving my health markers (blood pressure, cholesterol, inflammation markers) and losing excess fat by using the Zone diet principles in the past and now. I lost 40 lbs of fat in college in about 10 months. I got married and lapsed back into my old eating habits, so the weight came back. No surprise there! Look at my profile to see how I'm doing now.
Take your newfound knowledge of the glycemic load / glycemic index of foods, combine that with healthy lean meats and good-for-you fats with mild calorie restriction and you have a great recipe for a sustainable, nutritious, healthy diet.
I'll take a look at that website and let you know what I think. The best nutrition plan is one whose principles can be backed by many, many reputable sources. And kudos to you for buying the book! Gosh, there are so many people that only half-ass follow a plan and don't really do any research or READ about it, and usually go about trying to lose weight the wrong way by following ill-conceived notions about nutrition.