Blood Type Diet: What It Is and What Evidence Says
Last updated: 20 February 2026
The blood type diet (also known as “Eat Right 4 Your Type”) is an eating plan that recommends different foods depending on your ABO blood type–O, A, B, or AB. People often search for the O positive blood type diet, A positive blood type diet, or O blood type diet–the “positive” or “negative” refers to the Rhesus factor and does not change the diet’s food rules, which are based only on O, A, B, or AB. Scientific studies have not supported the idea that eating by blood type improves health or weight. We do not recommend the blood type diet. This page explains what it is, what each type is told to eat, what the evidence says, and what to do instead. Always talk to your doctor or dietitian before starting any diet.
Disclaimer: This page is for education only. DietaBest does not recommend the blood type diet–evidence does not support it. For healthy eating or weight loss, use evidence-based approaches with your doctor or dietitian. See our weight loss diet, Mediterranean diet, and calorie deficit guides.
Below: what the blood type diet is, how it is supposed to work (and what research says), what each type–including the O blood type diet and A positive blood type diet–is told to eat, risks and limitations, what to do instead, and answers to common questions. For evidence-based weight or calorie goals, use our calorie calculator and TDEE calculator with your doctor or dietitian.
What is the blood type diet?
The blood type diet was popularised by naturopath Peter D’Adamo in the book Eat Right 4 Your Type. The idea is that your ABO blood type (O, A, B, or AB) should determine what you eat: certain foods are said to be “beneficial,” “neutral,” or “avoid” for each type. For example, the O blood type diet (or O positive blood type diet–same food rules for type O) is often described as a “hunter” diet with more meat and fewer grains; the A positive blood type diet (or type A in general) is described as “agrarian,” with more plants and less meat. Type B and AB have their own suggested lists. The theory is not based on robust science: blood type determines antigen markers on red blood cells and has well-established roles in transfusion and some disease risks, but there is no good evidence that it determines which diet is best for you.
Core idea (we do not recommend)
- Type O: “Hunter”–more animal protein, fewer grains and legumes.
- Type A: “Agrarian”–more plant-based, less meat and dairy.
- Type B: “Nomad”–mixed diet, avoid some grains and nuts.
- Type AB: “Enigma”–combination of A and B rules.
Rhesus factor (positive or negative) does not change the diet in this system–so O positive blood type diet and O negative follow the same type-O food list.
How the blood type diet is supposed to work (and what evidence says)
The theory behind the blood type diet involves lectins–proteins in some foods that can bind cells. The claim is that certain lectins react with your blood type and cause harm, so you should avoid those foods. However, most lectins in food are reduced or destroyed by cooking, and the body handles them in ways that are not meaningfully tied to ABO type for diet choices. Systematic reviews and studies have looked at whether following a blood type diet improves health, weight, or cardiovascular risk. They have not found evidence that the diet works. Any benefits people report are likely from eating more whole foods and fewer processed ones in general–not from matching food to blood type. We do not recommend the blood type diet. For weight loss, a sustainable calorie deficit and a balanced diet work; use our calorie calculator and TDEE calculator with your doctor’s or dietitian’s guidance. For general healthy eating, see our Mediterranean diet or anti-inflammatory diet guides.
What each blood type is told to eat (for information only)
This table summarises what the blood type diet typically recommends for each type. We do not recommend following it. It is for information only–so you understand what an O positive blood type diet, A positive blood type diet, O blood type diet, or type B/AB plan usually looks like.
| Blood type | Typical “beneficial” foods | Typical “avoid” or limit |
|---|---|---|
| O (O positive / O negative) | Lean meat, fish, poultry, some vegetables, limited grains | Wheat, some legumes, dairy (in some versions) |
| A (A positive / A negative) | Vegetables, fruits, grains, legumes, less meat | Most meat, some dairy |
| B | Diverse: meat, dairy, grains, vegetables | Chicken, some grains (e.g. wheat), some nuts |
| AB | Mix of A and B: seafood, tofu, dairy, greens | Red meat, some grains and beans |
Evidence does not support tailoring your diet to your blood type. A balanced diet that suits your health, preferences, and goals is a better approach–see “What to do instead” below.
What the claims are vs what evidence says
The blood type diet claims that eating for your type can improve digestion, energy, weight, and disease risk. Research has not supported these claims. Studies comparing outcomes in people following type-specific diets have not found that blood type predicts benefit; when improvements occur, they are likely due to eating more whole foods and fewer processed ones, not to the blood-type rule. Major dietetic and scientific bodies do not endorse the blood type diet. We do not recommend it. For benefits backed by evidence, consider a balanced diet, the Mediterranean diet, or an anti-inflammatory diet, and for weight loss a sustainable calorie deficit–see our weight loss diet guide.
Risks and why we do not recommend the blood type diet
Following a blood type diet (including the O positive blood type diet or A positive blood type diet) can lead to:
- Unnecessary restriction: You may cut out nutritious foods (e.g. wholegrains or legumes for type O) without a proven benefit, which can make it harder to eat a balanced diet.
- False confidence: Relying on blood type instead of evidence-based advice may delay effective changes for weight or health.
- No proven upside: Since evidence does not support the theory, there is no demonstrated advantage over a standard balanced diet or evidence-based plan.
We do not recommend the blood type diet. If you have a medical condition or take medication, talk to your doctor or dietitian before changing your diet.
What to do instead
Instead of the blood type diet:
- Eat a balanced diet with plenty of vegetables, fruits, wholegrains, lean protein, and healthy fats. See our Mediterranean diet and heart-healthy diet guides.
- For weight loss: use our TDEE calculator and calorie calculator to estimate needs, then a moderate deficit with our calorie deficit calculator. Follow a sustainable plan–see our weight loss diet and calorie deficit diet guides.
- If you want a structured plan, choose one backed by evidence (e.g. Mediterranean, DASH, or a dietitian-designed plan) rather than blood type.
- Talk to your doctor or a dietitian for advice tailored to your health and goals.
Sample day (evidence-based alternative, not blood type diet)
We do not recommend a sample day for the blood type diet. Instead, here is an example of a balanced day that fits evidence-based healthy eating (e.g. Mediterranean-style):
- Breakfast: Porridge or wholegrain toast with nut butter, fruit, and a drink (e.g. milk or tea).
- Lunch: Salad or vegetables with chickpeas, grilled chicken, or fish; wholegrain bread or pasta; olive oil.
- Dinner: Grilled or baked fish or lean meat, vegetables, potato or rice, and a side salad.
- Snacks: Fruit, yogurt, nuts, or hummus with veg sticks.
This kind of pattern supports health and can be combined with a calorie deficit for weight loss. See our Mediterranean diet and weight loss diet guides for more ideas.
Frequently asked questions
The blood type diet (Eat Right 4 Your Type) is a plan that suggests eating certain foods and avoiding others based on your ABO blood type (O, A, B, or AB). It claims this improves health and weight. Scientific studies have not supported these claims. We do not recommend the blood type diet.
The O positive blood type diet (or O blood type diet) is the blood type diet for people with type O blood. It typically recommends more animal protein and fewer grains and legumes, based on the unproven idea that type O is the “hunter” type. Evidence does not support eating by blood type. We do not recommend it.
The A positive blood type diet is the blood type diet for people with type A blood. It usually recommends a more plant-based, vegetarian-leaning diet (the “agrarian” type). The theory is not supported by research. We do not recommend the blood type diet.
No. Reviews and studies have found no good evidence that eating according to your blood type improves health, weight, or disease risk. We do not recommend the blood type diet. For healthy eating, consider evidence-based options like the Mediterranean diet or a balanced weight loss diet with a calorie deficit.
Instead of the blood type diet, eat a balanced diet with plenty of vegetables, fruits, wholegrains, lean protein, and healthy fats. For weight loss, use a sustainable calorie deficit with our calorie and TDEE calculators. Consider our Mediterranean diet, anti-inflammatory diet, or weight loss diet guides. Talk to your doctor or dietitian.
We do not recommend following the blood type diet. If you want to manage weight, use our calorie calculator and TDEE calculator to estimate needs, then create a moderate deficit with our calorie deficit calculator. Pair that with a balanced diet (see our weight loss diet guide), not blood-type rules.
Summary
The blood type diet (Eat Right 4 Your Type) suggests eating different foods for types O, A, B, and AB–including the O positive blood type diet, A positive blood type diet, and O blood type diet. Scientific evidence does not support this approach. We do not recommend the blood type diet. For healthy eating, use a balanced diet or evidence-based plans like the Mediterranean diet or anti-inflammatory diet. For weight loss, use a sustainable calorie deficit with our calorie calculator, TDEE calculator, and weight loss diet guide. Always talk to your doctor or dietitian.
Use our calculators with this diet
Set your calorie target and plan meals with our free tools.
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Weight loss diet
Balanced eating with a calorie deficit for sustainable weight loss.
Cleanse & detox diet
Short-term plans claiming to detox. We do not recommend; body detoxes itself.
Commercial diet programs
Overview of programmes like Noom, Weight Watchers. Compare and choose with care.
Sources and further reading
This article is for general education. For the evidence on the blood type diet, see:
- Systematic reviews and studies on blood type and diet (e.g. in peer-reviewed journals)–reviews have not found support for the diet.
- Position statements from dietetic associations on evidence-based nutrition.
Last updated: 20 February 2026. Content is for educational purposes only and does not replace medical advice. We do not recommend the blood type diet.