Does the ‘blood type diet’ work?

What if your blood type could determine exactly what foods to eat and which to avoid based on your unique body chemistry? That’s exactly what the blood type diet promises.

Naturopathic physician Peter J. D’Adamo created the blood type diet in 1996.

The idea behind the diet is that your blood type determines the best foods for you to eat, based on what your ancestors with the same blood type ate. So, what’s healthy for you may not be healthy for your partner.

Why eat according to your blood type?

The diet claims to help you lose weight, improve digestion and boost your overall well-being.

According to D’Adamo, each of the four blood types has its own guidelines about specific foods to eat and to avoid.

If you have:

• Type O blood eat largely a plant-based diet with plenty of lean meats and cut out wheat and dairy.
• Type A blood eat a vegetarian-based diet high in carbohydrates and cut out meat.
• Type B and type AB blood eat a balanced omnivorous diet.

Does the blood type diet work?

While the premise of the diet is intriguing, there’s not enough scientific evidence to support it. In fact, this diet has not been proven in any clinical trials. That means the blood type diet is only based on a theory by D’Adamo. None of the claims can be proven.

You could lose weight on the diet because it contains many foods — particularly fruits and vegetables and lean meats — that are beneficial to your overall health. But that weight loss might not have anything to do with your eating foods in sync with your blood type.

People lose weight when they restrict calories. Since the blood type diet recommends avoiding highly processed foods such as desserts, chips and fast food, all of which contain a lot of calories, anyone may lose weight by avoiding these foods.

What is the best diet for weight loss?

As any dietitian will tell you, the key is to make a lifestyle change that includes meaningful dietary choices and continue them — not to follow a crash diet for a few weeks and then revert.

I tend to steer people toward the Mediterranean diet or a variation of it such as the DASH (dietary approaches for stopping hypertension) as well as anti- inflammatory diets. These diets are roadmaps for healthy eating that include many plant-based foods, lean proteins and whole grains — all of which have been shown to benefit health.

Many of the foods in the Mediterranean and DASH diets are also in the blood type diet. That’s another reason people may be successful at losing weight on the blood type diet — because it includes so many nutrient-dense foods.

Family history over blood type

In choosing a diet, consider your current health concerns and your family history. For example, if you have a strong family history of high blood pressure, eating many fruits and vegetables high in potassium and magnesium while avoiding sodium is ideal. If you have high blood sugar or a family history of it, follow a diet moderate in carbohydrates and eat mostly complex carbohydrates that contain fiber, such as whole fruits, vegetables and whole grains.

It’s wisest to eat foods proven to benefit your specific health condition or family history.

As a registered dietitian, I’m always looking for what’s healthy — regardless of blood type. Eat mostly unprocessed and plant-based foods. That’s the foundation of a nutritious diet.