When the story is better than the science

In 1996 a naturopathic physician named Peter D'Adamo published Eat Right 4 Your Type, which claimed that your blood group, O, A, B or AB, determines which foods your body thrives on. Type O, the oldest, should eat like a hunter: meat. Type A, the farmer: vegetarian. And so on. It sold millions of copies and it's still on shelves.

I'm including it for one reason, and it's an honest one. The science doesn't support it. In 2014 researchers at the University of Toronto tested the theory directly on fourteen hundred people and found that the diets did produce some benefits, but the benefits had nothing to do with blood type. The Type A diet helped everyone who ate it, regardless of their blood, because it was a reasonable mostly-plant diet. The story was decoration.

That makes this key a teaching about diets in general, and it belongs here, near the end of the table keys. Nearly every popular diet works, somewhat, for some people, for a while. Almost all of them work for the same few reasons: they cut processed food, they add vegetables, they create attention around eating, and they give the person a story that makes the change feel personal and meaningful. The story is often the active ingredient. People stick with what feels like it was made for them.

D'Adamo gave people a story that felt personal, and some of them ate better because of it. That's not nothing. It's also not blood type.

Vault Human's rule, which this key illustrates: keep the method when it's sound, hold the story lightly, and never confuse feeling chosen with being right. The set point from day six, the fullness from day one hundred and twenty-four, the protein from four days ago: those are the science. The rest is marketing.