Is the blood type diet the best for weight loss?

I thought it was time to continue with my quest of debunking popular weight loss diets. When people try to lose weight, it can be tempting to try a fad diet, but they often don’t work and have lots of drawbacks.

I’ve got a blog post here where I talk about why diets don’t work. I’ve also got a post here with what I think is the best diet for weight loss.

What is the blood type diet? 

The blood type diet was created by Dr Peter D’Adamo, a naturopathic doctor. Naturopathic medicine is an alternate form medicine that focuses on natural remedies to disease.

The blood type diet suggests that our blood holds the key to our health as it’s an important genetic factor. The diet says that depending on our blood types we’ll react to food differently. It also says that our blood type could predict our risk of certain diseases, our ability to respond to stress, and our gut microbiome.

The blood type diet is meant to consider the fact that nutrition isn’t a one size fits all approach. We all have different nutritional needs and will react to foods differently, so by eating for your blood type you can follow a more personal approach.

The blood type diet promises that by choosing the right food for your type you’ll have more energy, lead a longer healthier life, and lose weight. So, let’s get into what you can eat on this diet.

The blood types and what to eat: 

There are 4 blood types: A, B, AB, and O.

• Type A: these people should follow a diet that’s as ‘pure, fresh, and organic’ as possible, with food in its most natural state. The diet claims type A’s will do well on a vegetarian diet, focusing on grains, soy, and vegetables. Red meat is ‘toxic’ to this group.
• Type B: these people should focus on meat like goat or venison, green vegetables, eggs, and low fat dairy. Toxic foods include: chicken, corn, wheat, lentils, tomatoes, and peanuts.
• Type AB: these people should aim to eat tofu, seafood, dairy, grains, and green vegetables more often. They should avoid alcohol, caffeine, most meat, lectins (found in legumes), and cured meats. Type AB also should aim for smaller, more frequent meals and avoid mixing food groups in the same meal to help digestion.
• Type O: these people can have all types of lean meat, fruit, and vegetables. They should avoid caffeine, alcohol, wheat, grains, dairy, and legumes.

Negatives of the diet: 

It's not backed by science: 

The diet claims that eating for your blood type is the best option. But there isn’t any actual evidence to prove that. A study looked at people following the blood type diet and while they did lose weight, have lower cholesterol levels, and lower their insulin resistance, it wasn’t because they were eating foods linked to their blood type.

People had better results because they were eating healthier foods than they did before. Eating more fruits and vegetables while having less meat is really positive for your health. Who knew? And you’ll find that this happens regardless of your blood type.

It’s also worth noting that your diet is so more individual than blood type. Yes, generally we know what a healthy diet looks like for most of the population but even so, everyone reacts to food differently due to having unique genetics. So only looking at blood type when considering your diet, isn’t really specific enough. 

Nutrigenomics is an emerging science that looks at our diet and our risk to disease based on genes and biomarkers. It’s not developed enough to give meaningful advice, but it shows us that blood type isn’t the only thing to consider.

It's restrictive and impractical: 

Another theme I always notice when looking at fad diets, is that they’re very restrictive. The blood type diet has lists of food to avoid and doesn’t seem to leave room for much flexibility. Following a restrictive diet might not be the most realistic to stick to in the long term, especially if it’s very different to your current diet.

Restriction can also lead to bingeing, as when you restrict something, it makes you want it more. And the time that you let yourself have the forbidden food, you could overeat as you may see it as your one chance to have it.

The diet also isn’t very practical. For example, if you’re a type A, the diet recommends being a vegetarian. But what if you don’t want to be? Type B’s have to avoid chicken, but what if that’s the only meat you like? It doesn’t make sense to let your blood type determine your diet when it’s not even proven to make a difference.

Another angle to consider is within a family, people can have different blood types. For example, if your mum is a type A, and your dad is type B, then you could be a type A, B, AB, or O blood type depending on their genes. It doesn’t really make much sense for a family to be following multiple different diets. Surely your genes are already similar, so shouldn't you be eating the same? And that's not thinking about the shopping/meal preparation side of things either.

The image below shows the all possible blood type combinations 

Positives of the diet: 

I always include some positives of any diet I look at, as you have to give credit where it’s due.

Less ultra-processed food: 

A clear positive of this diet is the focus on whole foods. In the list of foods to eat, there’s no mention of any ultra-processed or typical ‘junk’ foods. Reducing your intake of ultra processed foods is never a bad thing as eating them more frequently can increase your risk of diseases such as cancer.

It also says you should try to limit simple carbohydrates as opposed to complex carbohydrates. This just means aiming for wholegrain versions of carbohydrates such as brown rice, granary bread, or brown pasta. These complex versions contain more fibre and take longer to digest so will limit the rise in your blood sugar levels after a meal. Having a more stabilised blood sugar level can reduce your cravings and aid in weight loss.

Encourages lifestyle changes: 

I know this isn’t diet related, but according to Dr D’Adamo there are also lifestyle changes you should make according to your blood type. These strategies include aiming for more physical activity if you’re a type O, or making sure you get 8 hours of sleep as a type B, for example. While diet is important, exercise and sleep are also crucial for your health so I can’t knock this.

It’s understandable that the blood type diet says it can also help you have more energy and live a healthier life. Making other lifestyle changes surrounding your sleep, exercise, and stress can definitely help.

Will the blood type diet lead to weight loss? 

After dissecting the pros and cons of the diet, it’s time to see if eating for your blood type will make you lose weight.

The short answer is yes, but it depends and isn’t likely to be long lasting.

The reason I say that it depends, is because it depends on what your diet was like before starting the blood type diet. If you already eat a diet based on whole foods, vegetables, and lean proteins, then eating for your blood type won’t be much different. So, you’re unlikely to notice any difference in weight.

If your normal diet is quite different to the blood type diet, and you eat more ultra-processed foods, or ‘unhealthy’ foods then switching to the diet will lead to weight loss. This is because whole foods are typically lower in calories than ultra processed foods.

Any weight loss you do have will only be maintained if you stick to the blood type diet. If you go back to eating more ultra-processed foods, then you’re likely to regain weight. As the diet is quite restrictive, it could be harder to stick to and mean the diet isn’t successful.

As you can see, the blood type diet isn’t the key to weight loss. Long lasting weight loss occurs when you make permanent changes to your lifestyle and sticking to the blood type diet is unlikely to be a permanent change you can make.

Key points: 

• The blood type diet is a fad diet that says what we eat is determined by our blood type.
• The diet says that type As should be vegetarian. Type Bs should avoid chicken, wheat, and corn. Type ABs should avoid meat and legumes. Type Os should avoid grains and dairy.
• There's no evidence to support that eating for your blood type specifically leads to health benefits. The diet can also be restrictive and impractical.
• The diet does encourage not eating ultra-processed foods, and eating more fruit and vegetables which is always a good thing.
• The blood type diet will lead to weight loss, but whether that weight loss is sustainable is another question.

I hope you enjoyed this post!

Bye for now 👋

References:

https://dadamo.com/txt/index.pl?2008

https://dadamo.com/ Blood type diet

https://www.bmj.com/company/newsroom/new-evidence-links-ultra-processed-foods-with-a-range-of-health-risks/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7946062/  Ultra-processed foods and weight gain

https://pubmed.ncbi.nlm.nih.gov/24454746/ Blood type diet is unscientific                 

https://www.genomicseducation.hee.nhs.uk/blog/nutrigenomics-your-genes-diet-health-what-you-need-to-know/ Nutrigenomics

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2692306/ Nutrigenomics