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What Is the Blood Type Diet and Does it Work for Weight Loss?

Diets come in all shapes and sizes, and there is no one single diet that is right for everyone. There are simply far too many factors (genetics, personal preference, finances, availability, etc.) at play to crown one particular diet as “the best.”


However, the healthiest diets have similar traits. In particular, they minimize the consumption of hyper-processed, refined goods and emphasize the intake of whole foods -- fruits, veggies, whole grains, lean proteins, and healthy fats.


Which diet is best for you is something that, frankly speaking, is only something that you can determine.


In recent years, with the increase in genetic testing there’s been an increase in the number of diet companies (read: marketing machines) that claim to be able to tell you the best diet for your physiology based on your blood type.


Is this the answer you’ve been looking for, or is the blood type diet just another entry in the long line of scams that annually plague the health and fitness arena?


Let’s discuss.


What is the Blood Type Diet?


The blood type diet is pretty much what it sounds like -- a way of eating based on your blood type.


The blood type diet was popularized by Dr. Peter D’Adamo, a naturopathic physician, in his 1996 book, Eat Right 4 Your Type. The publication was immensely successful, selling millions of copies and landing on the New York Times bestseller list.


In the book, Dr. D’Adamo claims that the optimal diet for an individual depends solely on the person’s blood type.


He posits that each blood type represents specific genetic traits of our ancestors, including on which diet they evolved to not only survive, but thrive.


Dr. D’Adamo gives each blood type a name that is associated with a type of ancestor, including:

  • Type A (agrarian/cultivator): individuals should eat a diet rich in plants, and avoid red meat because it’s supposedly “toxic” to their physiology.
  • Type B (nomad): individuals can eat plants and most meats (except pork or chicken) as well as some dairy. However, blood type B individuals should avoid/limit tomatoes, lentils, wheat, corn and several other foods.
  • Type AB (“enigma”): a cross between blood types A and B. Individuals may eat beans, grains, and seafood, while avoiding beef, chicken, corn, and kidney beans (though for some reason other beans are OK…)
  • Type O (the hunter): high-protein diet centered around meat, fish, poultry, and certain fruits and vegetables. It limits dairy, legumes, and grains (note: this sounds awfully close to the traditional paleo diet).


What Does Science Say?


To be honest, there is no comprehensive body of research investigating the supposed blood type diet.


The diet centers around a particular type of protein called lectins. If you’re familiar with the paleo/primal diet, then you’ve heard the word thrown around more than a few times.


Dr. D’Adamo claims that eating the wrong types of lectins could result in agglutination (clumping together of red blood cells).


To be fair, there is some evidence that a small (very small) percentage of lectins in raw, uncooked legumes, could have agglutinating activity specific to a particular blood type. For instance, consuming raw lima beans may interact only with the red blood cells in people with blood type A.[1]


Then again, who is really consuming raw legumes in the first place?!


Moreover, there is some scientific evidence to suggest that the majority of lectins that lead to agglutination react with all ABO blood types.[2]


In other words, lectins are NOT blood-type specific, with the exception of a few varieties of raw legumes, as we mentioned above.


Furthermore, if legumes/beans are prepared in their traditional manner (i.e. the way most people still prepare them), they are soaked and then cooked for a considerable length of time, which destroys the hazardous lectins (as well as various other “anti-nutrients”).[3]


Basically, there is no hard evidence behind the blood type diet, particularly when it comes to lectins and only eating/avoiding certain foods because of your blood type.


Now, we should mention that the field of genetics is evolving at a rapid pace, and researchers have identified several genetic markers which may lead an individual to have a higher or lower risk for certain diseases.


Still, there is no research to date showing that this to have anything to do with diet.


To top it off, a 2013 systematic review that examined data from over a thousand scientific studies NO well-designed research proving any health effects of the blood type diet.[4]




Like many of the fad diets that we encounter year in and year out, the blood type diet is more bark than bite. There might be some small fraction of evidence at the core of the diet, but the proponents of it have blown it very much out of proportion and made extrapolations that are far beyond reasonable.


Is it possible that individual following the blood type diet may have experienced weight loss and improved markers of metabolic health?




But, is that because they ate according to their diet?


No. It is more likely that their new way of eating reduced their overall calorie intake, eliminated a lot of the garbage they were eating before, and significantly increased their intake of micronutrient and fiber-rich foods, which are known to have beneficial effects on weight loss and cardiometabolic health.


At the end of the day, you don’t need to follow any sort of fad diet to lose weight, build muscle, or get results. You do need to eat the proper amount of calories and macronutrients to support your goals.


And, this can easily be accomplished by logging into the 1UP Fitness App, available on both Apple & Google Play. The app not only provides calorie intake suggestions for helping you meet your fitness and physique goals, but you can also easily track your food intake as well as your workouts. You also get access to our private Facebook group where you can interact with other like-minded individuals for support and encouragement as well as enter our Transformation Challenge where you can win cash prizes!



  1. Nathan Sharon, Halina Lis, History of lectins: from hemagglutinins to biological recognition molecules, Glycobiology, Volume 14, Issue 11, November 2004, Pages 53R–62R, https://doi.org/10.1093/glycob/cwh122
  2. Nachbar MS, Oppenheim JD. Lectins in the United States diet: a survey of lectins in commonly consumed foods and a review of the literature. Am J Clin Nutr. 1980 Nov;33(11):2338-45. doi: 10.1093/ajcn/33.11.2338. PMID: 7001881.
  3. Lajolo FM, Genovese MI. Nutritional significance of lectins and enzyme inhibitors from legumes. J Agric Food Chem. 2002 Oct 23;50(22):6592-8. doi: 10.1021/jf020191k. PMID: 12381157.
  4. Cusack L, De Buck E, Compernolle V, Vandekerckhove P. Blood type diets lack supporting evidence: a systematic review. Am J Clin Nutr. 2013 Jul;98(1):99-104. doi: 10.3945/ajcn.113.058693. Epub 2013 May 22. PMID: 23697707.

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