The reason I believe this: He doesn't come out and say this: Don't eat: fast-food (about 20% of our food intake), junk food, soda, processed food (about 70% of our food intake), and minimize consumption of sugar. And, there's absolutely no discussion of exercise. That's like purchasing an expensive car without putting gas in it ... it ain't gonna run.
As I've stated a "zillion" times, if you follow the overlapping area below, you can pretty much eat in any "diet camp". Oh yeah, and you can go back and forth to each one. Hey, I eat meat, I eat plants (veggies and fruit), fish, beans, legumes, grains, and more. And to steal a slogan: I'm lovin' it.
The most important thing: Identify a lifestyle plan that works for you.