My wife and I subscribe to the theory that different diets are better for different people, and it has some relationship to blood types. I don't think it's as simple as "this type eats this food" but I definitely think there is something to it.

I am type O and definitely do best on the Paleo type diet. Type O's were supposedly the "hunter gatherers" so this fits the theory. My wife is type A and definitely does best on a grain and vegetable based diet. Her diet is not Paleo at all and she would not do well with it, she can't eat that much meat and fat and needs her starches and carbs.

We often ask friends and family what their blood types and dietary preferences are and the data points we get are way too common and correlated to be coincidence. Almost without exception, the type O's that we know are enthusiastic meat eaters, while the type A's and B's are either omnivorous or prefer various starches and grains much more than the type O's. This is all anecdotal but I think there is something to it.

This isn't to say that everyone we talk to fits into 2 or 3 diets, it is just a tendency. For example we ask people, if your plate had meat, salad and pasta/rice on it, what would your first bite be? For me, it is always the meat, in fact sometimes I will finish the meat before going on to anything else. My wife does the same with the starch. The answer that people have to this question says something about their general dietary preferences.

I think the science behind books like "Eat Right 4 Your Type" is iffy at best, and maybe it doesn't have to do with blood type at all, but some other aspect of human lineage that is itself correlated with blood type. Doesn't it make sense that, among the billions of people in the world, people of different genetic backgrounds need different diets based on how they evolved over the preceding thousands of years? There are studies that show that humans evolve in periods as short a 100 years, so over 10,000 years or 300-400 generations there is ample time for a culture to become adapted to a particular diet.

This would also explain why some people do better on the Paleo diet than others. It is clear from the feedback on this site that the diet isn't for everyone -- some people have spectacular success, and others just have problems.

I would be curious to see the results of a poll of the blood type of people that are successful with the Paleo diet. My guess is that there would be an uncommonly high number of type O's compared to the general population.

well, for one thing, the blood type diet claims that "O" is the oldest blood type and makes its recommendations based on that, but science has it fairly well accepted that that premise is wrong and "A" is likely the oldest blood type (this info was available when that book was written)... so you gotta figure if they couldn't get that basic fact right then...

Blood type refers to the presence of different classes of surface glycoproteins on red blood cells. These proteins are entirely irrelevant to the physiology of nutrition or digestion. That is unless you've been pumped with blood of a different type. Then, your digestion may be affected, but that'll be the least of your worries.

I like Robb Wolf's answer: "It works if you assume that everyone is Type O." I'm assuming that the recommendation for Type O is a Paleo-type diet.

In other words, no your blood type has no affect on how you metabolize food.

My blood type (A) recommends a vegetarian, agrarian diet.

I'm allergic or intolerant of legumes and grains. Severely. I've had leaky gut and gastric upset most of my life, which accelerated in my late 20's with inability to eat practically anything without getting horrendously sick... and then I found Paleo.

So, if I "ate right for my blood type", I'd be dead. Unless you can be pulse/gluten free and still be a vegan (30BAD maybe? I think I'd get sick of that pretty quickly too).

The diet partially succeeds because it introduces structure to an otherwise SAD dieter's existence. When you introduce some structure and cognizance of what you are stuffing in your cake hole, some success happens.

Also, Coach Dan John's constant reminder in his books "Everything works for about 6 weeks".

An excellent rebuttal of the blood type diet by Don Matesz - http://donmatesz.blogspot.com/2010/12/blood-type-diet-primal-perspective.html

This stuff is only confusing people out there who don't have the background to see through right away. My Mom read it and believed it, because it sounds "scientific". It took me a while of very delicate explanation that it's ok for her to eat beef...

idiots. they just want to make money, but they can hurt people over it.

My blood type is A+. I tried becoming a vegetarian (not because of my blood type, but for ethical reasons) and was never more sick in my entire life. I had chronic bronchial infections, recurrence of long-gone childhood asthma, allergies worsened, chemical sensitivities worsened, etc. I didn't put 2 and 2 together at the time, but when I'd finally had enough and went to a naturopath that started me down the road to Paleo (my naturopath is a Vegan who is now considering changing to Paleo because of my 180 turnaround, mind you). I became fairly strict Paleo a little over a year ago (albeit I do eat a bit too much dark chocolate and indulge in macadamia nuts too often) - no dairy, no nightshades. Mostly meat, fat and veggies and fruit. I would consider myself low carb to moderate carb depending on the fruit that is in season. :) I feel the best I've felt in my 43 years of life Off the charts energy, haven't been sick since I started, haven't had a headache in over a year (serious migraines before Paleo). If I had decided to try the blood type diet I can't imagine in what horrible condition I would be in right now. We are all designed to eat hunter/gatherer diets. Period.

Until we had regular blood typing available, how would a human have known what blood type they were? They'd have no idea. How would we evolve a system for feeding ourselves that required the invention of technology that wouldn't be readily available until a couple hundred thousand years later? From first principles (we'll ignore that RBCs don't digest food, adding another level of biological implausibility) this makes zero sense.

Despite the quasi-science of it all the blood type diet seems to work for a lot of people, not just for weight loss but to help heal certain medical conditions over time. I am O +, and supposed to eat a simple low carb hunter/gatherer diet( basically the Paleo , which I am now embracing!) Through trial and error, over many years, I found that it IS really the best way to eat for me- I have tons of energy, feel great and my skin and muscle tone improve, my weight stays stable, joints feel better etc. When I was in college all my artsy friends were vegetarian, and I bought into that for a while, with disastrous results. I had NO energy at all, was terribly hungry all the time, had digestive/skin issues from eating the legumes, even developed anemia, even though I was taking supplements, eating lots of greens etc. My doctor told me to start eating meat again or else. And when I did I felt like superwoman! Lesson learned. I think everyone has to experiment and find out what works for their body. Id be curious if any of you have seen improvement with arthritis after eating Paleo for a while . According to D'Adamo type Os get the worst forms of arthritis and it is aggravated by grains, dairy and refined sugars, which they should avoid. Seems to be true for me. Long live us carnivores!

One judge of how "real" a diet is based on the number of books on the subject found in secondhand bookstores. I often see books on blood type diet, zone diets, Atkins diet, etc. Although in part this means these books sold well, I view it as an indicator the diets have not been successful ... or the books are simply bad. Interestingly, I never see Paleo diet books in these shops ... and I believe these books have been selling fairly well. Makes me believe people keep these books as reference as they stick with the Paleo diet for the long term.

_Lazza

Blood type diet is just another fad diet. Along the same vein, HCG diet, 17-day diet, Dukane diet, etc ad nausea are fads.

I don't prescribe to "blood type" being an indicator of how and what you should eat, but I think there are all types of healthy eating options. I've personally been vegan, vegetarian and now mostly what one would call "paleo" (I stick with unprocessed foods and no grains/legumes and very little sugar) and I will say that while I was vegan/vegetarian my health was not optimal even though I was technically eating "healthy" foods..I was not a junk food vegan by any means but couldn't seem to sustain my energy or lose weight or just feel "good". It was a 4 year process...I finally decided to go back to eating meats...I felt much better. I do know there are some folks who do very well on vegan diet and for whatever reason it works...I think it's just all individual and you have to listen to your body and really gauge how foods make you feel. Unless you eat only raw foods or only vegetables and fruits and nuts and seeds you'll be ingesting a lot of processed foods which in my opinion (which probably doesn't count for much) isn't the best option. What is making you feel the need to go vegan? If it's animal "rights" issues you can always try to opt for humane practice farms, etc. If it's health issues then not sure what to say other than "listen to your body" (again).

I can give credit to the blood type diet for one thing. I am a type O and when it came out in the mid-1990s, it helped me overcome the idea that a semi-vegetarian diet (white meat) was ideal for me. Back in those days, I frequented (mostly trolled :) the ER4YT forum and the Type As, who were recommended quasi-vegetarian diets), fared the worst of all on the diet. I would call it a "Fad diet" and unfortunately, Dr. D'Adamo could never fall out of love with his own theory and touts it to this very day.

Karin is right - Hcg is an amazing weight loss program that totally works. I have loads of friends who've been on it with astounding results. It has changed the shape of my body and it's quite amazing what it does to your mind and your mental link to food. It is brilliant, although it's hard to assess it without actually doing it yourself or having people around you doing it. It's extraordinary, and the doctor that formulated the program several decades ago had a brilliant mind. Wikipedia states that he, amongst other things

Dr. Albert T. W. Simeons, (1900 - 1970), english endocrinologist, schooled in Germany. During short stay in Africa he wanted to find a cure for Tropical Diseases. Then he went to India in 1930. He was awarded with the Red Cross Order of Merit for his discoveries in new methods that would lead to a cure for malaria.

He wrote a wonderful book Man's Presumptuous Brain which examines the psychosomatic root of many conditions. Interesting and ahead of his time.

You shouldn't go vegetarian because the blood group book tells you to, but many years ago I believed it and went pescetarian. I felt a lot better, and it led me on the path to vegetarian, then vegan to fruitarian. I have never felt better in all my life. I don't believe in the blood group diet, but I do believe that all humans will be healthier without meat, eggs and dairy, so long as those products are replaced with whole fruits and vegetables rather than processed crap. I would suggest trying it. You will feel better without the meat and dairy!