Health Library

The Blood Type Diet


The blood type diet is based on your blood type. If your blood type is A, you should eat vegetarian foods, if it is type O, you should eat mostly meat and not eat grains, and if it is type B, you can eat many types of food, such as dairy, which you cannot eat for type A and O.

How Might This Work?

This weight loss plan was made by Dr. Peter D’Adamo, a naturopathic doctor. He thinks that eating foods that are right for your blood type will make you feel better. He also thinks you will be less likely to store the food away as fat and less likely to have some health problems.

Dr. D’Adamo thinks blood type is an evolutionary marker that points to which foods are best for your body and which foods can harm it. He thinks that we should be eating what our ancestors with the same blood type ate. He says type Os were meat-eating hunter-gatherers, while type As were vegetarian farmers, and type Bs were nomads, eating many more types of food.

What is Involved?

Dr. D’Adamo advises that all people eat mostly fresh, natural foods, and cut out processed foods. Chocolate, coffee, and alcohol should not be eaten. Dr. D’Adamo also gives exercise advice. Here are the eating plans:

Blood Type Foods That Can Be Eaten Foods That Should Not Be Eaten Exercise

Type A

Vegetables, fruit, grains, beans, legumes, nuts, and seeds Dairy, meat, fish, poultry, eggs, and processed foods Calming exercise like golf or yoga

Type B

Vegetables, fruit, grains, beans, legumes, meat, poultry, fish, eggs, and dairy Nuts, seeds, and processed foods Moderate-intensity exercise like walking, hiking, and tennis

Type AB

Foods on both the Type A and Type B diets are all okay, but a vegan diet is best most of the time Processed foods Both calming and moderate-intensity exercise

Type O

Meat, poultry, fish, and olive oil; limit: certain vegetables, nuts, seeds, and eggs Dairy, grains like cereal; bread, pasta, and rice; beans and processed foods Vigorous exercise like running

What Does the Research Say?

This weight loss plan is not supported by evidence.

Are There Any Concerns?

The type A and O diets are very strict. They remove whole groups of food. This is an easy way to cut down on calories and will lead to some weight loss. But you are also taking out vitamins, minerals, and other nutrients that you need.

Dr. D’Adamo advises specific supplements for each blood type to make sure you meet all your nutrient needs. Supplements can give you a little extra nutrition, but they should not be used as a substitute for a well balanced diet . Dr. D’Adamo encourages dieters to buy from his own line of supplements that were made to go with his weight loss plans.

Bottom Line

You should not try this weight loss plan. It greatly limits the food you can eat. This makes it hard to meet nutrient needs and follow the plan for a long time. People who want to lose weight should choose a weight loss plan that is backed by evidence and matches their lifestyle.


Eat Right—American Dietetic Association

National Institute of Diabetes and Digestive and Kidney Diseases

Canadian Resources

Dietitians of Canada

Health Canada


Blood type diet. Every Diet website. Available at: Updated January 21, 2018. Accessed June 18, 2019.