As with many diets, the restrictions of the blood type diet are plentiful, especially when you consider that for certain blood types, entire food groups are off limits.
For people with type A blood, be prepared for what is most likely going to be a big change in lifestyle. The blood type diet recognizes that your ancestors are most likely of European or Japanese descent [source: Cronin]. These ancestors were field workers who mastered farming and harvesting, so the diet designates vegetarianism as your best bet for a healthy lifestyle [source: Asp]. It recommends that you stick to carbohydrate-filled, low-fat fruits and vegetables and very little meat or dairy [source: Kellow].
For those of you with type B blood, you can enjoy a little more freedom than the other blood types. Thought to have descended from Europe, India and Eastern Asia, these ancestors roamed all over. Therefore, Dr. D'Adamo believes that their bodies adapted many times over, making their blood capable of accepting any available nourishment [sources: Cronin, Kellow]. Dr. D'Adamo suggests staying away from processed foods, as they lack many essential nutrients, and mixing up your diet with proteins and carbs [source: Diet Channel].
Naturally, AB is a combination of A and B. People with AB blood should find a happy medium between the vegetarian lifestyle of their A side and the varied lifestyle of their B. According to Dr. D'Adamo, the best approach is to take on the vegetarian lifestyle, while incorporating small amounts of lean protein like fish or chicken. He also proposes that you take the same approach to dairy [source: Kellow].
Type O is the most common blood type, and is said to have descended from Africans and American Indians [source: Cronin]. These ancestors were hunters and survived by eating meat. Therefore, Dr. D'Adamo says it's only natural to enjoy a carnivore's lifestyle. This blood type should get a fair amount of protein from meat, with fruits and vegetables contributing to their diet as well. Avoid dairy, wheat, pasta and most of the foods that are said to complement the A blood type [sources: Diet Channel, Kellow].
Once you know your blood type, you can do further research to learn more specific information about the foods you should be eating. For now, check out the links of the next page to expand on what you've already learned.