Is there any truth to a new diet that is based on your blood type? I read that if your blood type is O, then you can lose weight by eating a high protein diet (lots of meat). I'm trying to lose weight but I'm not sure what type of food to stay away from and what type of food is good for me. Should I be eating pasta or taking in a lot of carbohydrates?

Blood Type O

Dear Blood Type O,

The diet you are referring to was published by Peter D'Adamo, ND, in his book "Eat Right 4 Your Type." D'Adamo is a naturopathic doctor, who developed the concept of blood group-based diets during his studies to become a naturopath. He has since elaborated these ideas into a best-selling book, which states that we should eat foods that somehow match our blood groups and therefore our putative ancestral eating habits.

There is no scientific evidence to support his contentions concerning the relationship of diet to blood groups, or that people with certain blood groups will do better eating certain foods. If you look carefully at the diets he prescribes for weight loss, you will notice that they are low in calories, no matter what foods are included -- and a diet low in calories will result in weight loss.

Fad diets -- and the Blood Group diets are fad diets -- can lead to poor health. For example the diet D'Adamo prescribes a diet high in animal fat for people with blood type O. There is strong scientific data that correlates the consumption of these foods with heart disease, certain types of cancer and strokes. To detect whether a diet is a fad diet, visit the American Heart Association's page on how to recognize fad diets.