Followers of the controversial Blood Type Diet say that sticking to a diet based on your blood type can help you lose weight, look fantastic and feel healthier and happier. But experts disagree.

Created by naturopath Dr. Peter D'Adamo, the Blood Type Diet has received rave reviews from big-name celebrities like Liz Hurley, Courtney Cox-Arquette and Martine McCutcheon – and D'Adamo’s New York Times bestselling book on the subject, Eat Right 4 Your Type, has been translated into over 50 languages, making the Blood Type Diet one of the most talked about weightloss trends on the planet for years. But does it actually work?

What is the Blood Type Diet?

The idea is that “one size fits all” diets don’t work, as everyone has specific dietary needs depending on their blood type. There are four blood types, and D'Adamo says that your blood type has an impact on your digestion, so that you’ll respond differently to different foods, and digest and absorb certain foods more efficiently. The upshot is that you’ll lose weight if you stick to those foods that are specifically beneficial for your blood type.

But how did D'Adamo come up with these beneficial foods? He’s based it on history, which is one of the reasons why most nutritionists are unconvinced by this diet. According to D'Adamo, the different blood groups emerged at different times in history, so you should stick to eating and exercising as your blood type’s ancestors did back in the day.

So all you have to do, the theory goes, is find out your blood type by asking your doctor for a test or donating blood, and then follow a specific diet based on that specific blood type, stocking up on beneficial foods and avoiding ones that don’t agree with your genes.

Blood Type Diet Information: What Should Each Blood Type Eat?

People with Blood Group O, the most common blood group, are supposed to stick to a “hunter gatherer” high protein, low carb, meat and fish based diet. You can eat fruit, vegetables, eggs and nuts in moderation, but dairy and carbs like bread, pasta and rice should be avoided. It’s a typical low-carb diet, similar to popular diets like the Atkins. Like the hunter gatherers of the past, lots of vigorous exercise is recommended too.

People with Blood Group A, the second most common blood group, should thrive on a “cultivator” or farmer’s diet, which would be vegetarian based. You’re allowed lots of vegetables and grains, including typical diet no-nos like pasta and rice, but should avoid dairy products and meat. D'Adamo also recommends slower, less vigorous exercises such as yoga and walking as best for Blood Group As.

People with the more unusual Blood Group B are probably the luckiest, since they’re allowed a “nomadic”, varied diet, including most foods such as meat, dairy, grains and vegetables – in fact this is the only group that is supposed to thrive on dairy products. You’re still restricted though, as carbs, nuts and seeds should only be eaten in moderation. Group Bs should stick to exercises that keep you alert and interested, like tennis or dancing.

People with Blood Group AB, which is the newest blood type, and the most rare, are called the “enigma” by D'Adamo and should eat a mixture of Group A and Group B foods – so a variety of options including meat, fish and dairy are allowed in moderation but with the emphasis on vegetables. Group ABs should do moderate and varied exercises.

The Blood Type Diet: Carrying Out the Diet

If you do decide to take the plunge and follow the Blood Type Diet, you don’t need to switch over overnight – ‘avoid’ foods haven’t killed you yet – but according to this diet, in order to get healthy, happy and slim, you do need to gradually eat more of the beneficial foods and cut negative foods out. You don’t need to give ‘bad’ foods up entirely though. D'Adamo says you only need to stick to the diet 70% of the time, so you can occasionally snack on ‘avoid’ foods and add small amounts of these foods to recipes.

You’ll also find a huge number of food substitutes are available – think rice and soy milk, sweet potatoes instead of white ones and rice cereal instead of wheat.

The Blood Type Diet Information: Does it Actually Work?

It’s a very controversial theory, with most experts saying that the diet is absolute rubbish.

For a start, there’s no scientific basis to back all this up and D'Adamo has never produced any evidence or research to prove it works, despite stating in several of his books that he was involved in clinical research trials, the results of which he never published. Plus, scientists have no idea when exactly each blood group developed, or what people were eating back then, as we’re talking tens of thousands of years BC – in fact, many believe Group A developed first.

And on top of being seemingly random, nutritionists say cutting out whole food groups as this diet advises could be dangerous, resulting in a lack of essential nutrients.

Judith Wills, author of bestselling nutrition book The Diet Bible, says the Blood Type Diet is ridiculous. “There’s no proper science behind this at all,” she says. “If you aren't allergic, then cutting out one of the major groups such as wheat or dairy may cause shortfalls in certain nutrients or even calorie intake and therefore may not be a good idea.”

Caroline Stokes, a Nutrition Scientist working at the British Nutrition Foundation, agrees.

“Overall, I would be against this diet as there is a general lack of science around it,” she explains, “Specifically, this plan involves cutting out all types of foods for no logical explanation (people with blood group A are not even allowed bananas - usually the dieter’s favourite food!), so it could well mean you’ll end up with an unbalanced diet and a low intake of certain nutrients.”

And Stokes says that if you’re cooking for a family, it may be difficult if there are different blood type members to cater for. Plus, for vegetarians, the diet may be extremely difficult to stick to, depending on your blood type.

“With so many foods restricted, the diet is likely to become monotonous unless you are prepared to try foods like sprouted wheat bread for example,” she added.

The verdict? If you stick to the Blood Type Diet, it’s likely you will lose some weight initially, but you’ll do so at the risk of your health and you’re sure to pile the pounds back on as soon as you stop dieting – which will probably happen quickly, as this diet is simply not sustainable.

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