Oddbean

My opinion is there's no reason for optimal diet and blood type to coincide, so the core thesis is basically nonsense But from what I understand the diets recommended are not totally crazy so whichever one is recommended for you might work OK I am of the opinion that something in the carnivore/Paleo/keto spectrum is optimum for basically everyone.

TLDR on the diets for blood types? Agree with you on the clean keto/paleo/carnivore, but don’t think the body is meant to be in constant ketosis regardless of how much more efficient your brain can utilize ketones.

The reason I feel there's something to it is it matches the experiences I have had with things that it says for my blood type to completely avoid. I basically have gone through a major process to find the optimal diet for myself where I feel the best & I did all this work without books or YT but by plain elimination. When reality matches a theory how likely is it to be coincidence?

Which one is your blood type? Based on WebMD it seems type O & B are both told to avoid plants which are common irritants (like grains and beans) https://www.webmd.com/diet/a-z/blood-type-diet I agree with avoiding those things. I would recommend everyone do so, though, not just people with type O or B blood. As to how likely it is to be a coincidence: those two types roughly match my conception of a healthy human diet while type A and AB don't. So about 50/50. More generally, the odds of a coincidence are about 1 in 4 (assuming there's no correlation at all between blood type and optimal diet and remaining agnostic about what constitutes optimal diet).

There's a lot to breakdown here but it's not a 1/4 chance for coincidence, as each food is broken down individually to even different fish species for example. Even more interesting in that book is seeing the difference in how blood type affects outcomes from parkisons to cancers to autism, even which blood types are most succeptible to alcoholism.

There's 4 diets. If there's zero correlation between your blood type and which of those diets is best for you, there's still a 1 in 4 chance that your blood type will match the best diet (of the 4) for you. This does not depend on the complexity of the diets.

That's where I didn't really focus in, Mostly focused on what's recommended & what's to avoid for all blood types. Then obviously some confirmation bias after my elimination diets/ intuitive eating. But yeah I didn't realize some people are probably following it to the letter for their blood types without confirming with how they feel / placebo / going from a shitty diet to only whole foods.