What do the experts say?
Medical experts universally agree that the theory is nonsense, and say there is absolutely no link between our blood group and the diet we eat. Consequently you won't find qualified nutritionists or dietitians recommending this diet.

There are also several concerns, namely that the diets recommended for blood groups O and A are considerably limited and cut out major groups of foods.

In the long term, this can result in a poor intake of nutrients needed for good health. Cutting out dairy products, for example, will lead to poor intakes of calcium, which can put you at risk of osteoporosis (brittle bone disease), while avoiding meat can result in low intakes of iron, which can lead to anaemia.

But will the diet help me lose weight?
Almost certainly, but this is because each of the diets for the four blood types eliminates specific groups of food such as bread and cereals, dairy products or meat and fish. Dr D'Adamo doesn't give any indication about how much weight you'll lose, it will depend on how much you restrict your food intake.

Are there any pros?
There are not many positive things to say about this diet, which is clearly based on science fiction rather than science fact. However, as with any diet, it will get you thinking about what you are currently eating, with the result that you may start to make changes to your diet. Added to this, the blood type diet recommends eating fresh, natural foods and so can help you de-junk your diet by cutting out processed foods, takeaways, booze, chocolate and too many cups of coffee - all of which our ancestors missed out on!

And the cons?
There are plenty. On a practical level, it is almoust impossible for everyone in the family to follow the diet, if they have different blood groups! But most importantly, it's just another cranky way of getting people to cut calories - and the most worrying thing about this is that while you'll probably lose weight, it could also affect your health in the long term. Nevertheless, if you're still adamant about giving it a go, it's best to follow it for just a short time (one week or less) and use it to kick-start a longer-term, healthy, weight-loss plan.