The Blood Type Diet Remains on the Fiction Bookshelf


In 1996 a naturopath published “Eat Right 4 Your Type”, a diet book purporting that people with different blood types would benefit from different diets. There are a lot more people who want to lose weight than who want to exercise skepticism, so the book became a multi-million dollar success.

As an aside, the proliferation of myriad different diets on the market should make us suspect that none of them are very effective. For example, there were countless ineffective but widely used remedies for pneumonia before the discovery of penicillin. Afterwards, there was only one treatment.

” target=”_blank”>investigators at the University of Toronto published a study in PLOS ONE testing the blood-type diet. I’ll spare you the details of the study, but it showed that people who followed most of the diets lost weight independently of whether they were following the diet suggested for their blood type or for some other blood type.

The study wasn't randomized. It just looked at the diets that people were already eating. My regular readers know that I don’t give observational studies much weight. I would never recommend a new medication or surgery based on a non-randomized study (because I would cling to the null hypothesis). But given a diet that already had a lot going against it and no evidence for it, this is another suggestion that you should choose what you eat based on your belt size not your blood type.

Learn more:

” target=”_blank”>Blood Type Diet – Disproved (Neurologica Blog)
” target=”_blank”>Eat Right for Your Belt Size, Not Your Blood Type (my post from 2011)

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