This diet is a complete scam, has absolutely no scientific basis, but has a concept so interesting it’s worth including—if only to give an idea of how crazy diets can get. Its basic principle: a person’s blood type determines the kind of foods they should eat. Bizarre? Read on.

According to some scientists, our blood type is an evolutionary indicator of the food of our ancestors. Type A’s were farmers (so you should eat vegetable products), Type B’s were omnivores (so you should eat dairy, meat and vegetables), and Type O’s were hunter-gatherers (bring on the meat!).

All this is described in Peter D’Amano’s Book, “Eat Right for your Type” where he declares that those with Type O “can’t tolerate wheat” but doesn’t provide any support outside of his own valuable opinion. There have been no independent studies on whether or not blood type affects the way we digest or react to food.