Peter D'Adamo's blood type diet books have been used by thousands of people to lose weight and improve their overall health.

The blood type diet books help to explain how this theory works. D'Adamo believes that our blood types determine key factors in our physiology, including how our body reacts to certain foods.

In his blood type diet books he details how to change your eating so that the food you eat is right for you. Once you have established your blood type, you can then figure out which foods will improve your health and help you to lose weight.

There are titles for each of the different types - A, O, etc, plus others that detail how this approach can help prevent or treat allergies, and major illnesses including cancer and arthritis.

Finally there's cookbooks filled with recipes suitable for each of the different groups.

This is a controversial approach - one the one hand there are scientists who say that there is no evidence to support the theory, while on the other hand are the thousands of people who have lost weight and improved their health by following the recommendations.

So what do you do? Check out the books available, and make up your own mind!