The book is successful because it (fallaciously) explains a very real phenomenon that’s confusing to most people- there’s no one healthy and satisfying way to eat for everyone.

My sister and I have two nearly opposite digestive issues: she has celiac’s, and I can’t digest meat. She lost weight and got happier when she cut most grains out, but when I switched to mostly greens and grains, my acne cleared up, I slept better, and I took better shits (I had already been eating greens). Now we each have a medically documented digestive issue, so there’s clearly something else causing this, but we didn’t know that as kids. At that point, we just saw siblings who obviously reacted very differently to the same nutritional input.

A book like this might have gotten my mom, especially because I’m type A (my sister’s either A or O, so there’s a chance it would have really gotten her and made thanksgiving super annoying). I don’t think it’s scientific, and I do think it’s morally reprehensible to just scam people like this, but I think there is something (or many somethings) we’re missing, and this book might be right that some do better with meat and some with grains. It’s poppycock that it has to do with blood type (B can digest dairy, so that means there’s basically no Chinese people over 70 with type B blood, right?), but I understand why people latch onto it.