Blood Type Dieting

The blood type diet was originally created by Dr. Peter D'Adamo in his book, "Eat Right 4 Your Type." It is based on the principle that a person's body interacts with and digests food differently based on her blood type. Your blood type may indicate that you need to eat primarily meat products or that you should be a vegetarian. However, health experts are skeptical that how we process food has any relationship to our blood type. Most major health organizations, like the Mayo Clinic, have not found scientific evidence to back up the claims made by this diet.

Principles

• The blood type diet was created to address a puzzling question in the weight loss field--why do some people lose weight on certain diets and not others? According to Dr. D'Adamo, a person's blood type explains the lack of consistent results. In the blood type diet, dieters are given specific recommendations on what to eat and what not to eat, based on their blood type of O, AB, A or B. Certain foods are suitable for some blood types and not others because of proteins in food called lectins. According to the diet, lectins interact differently with people of different blood types.

Food Choices

• What you eat on the blood type diet will depend, naturally, on your blood type. Those with type O blood are urged to focus their diets on animal proteins and avoid dairy and foods with gluten, including wheat products, corn and lentils. Type A dieters are recommended to follow a vegetarian diet, with a focus on fresh organic produce and whole grains. Those with type B and AB blood are lucky in that their systems can tolerate a more diverse diet, and Dr. D'Adamo recommends a healthy combination of animal protein, whole grains and produce for these dieters. Within the blood type book, Dr. D'Adamo lists the best foods--and foods to avoid--for each blood type.

Exercise

• Your blood type will also influence the type of exercise you perform on the blood type diet. Type O dieters require large amounts of physical activity and do best with high-intensity cardio exercise like aerobics or running at least five days a week. Those with type B and AB blood require less exercise than type O dieters, but are still recommended to perform moderate amounts of exercise--30 minutes a few times a week--in sports like bicycling or swimming. Type A dieters, on the other hand, require calming exercises like yoga.

Weight Loss

• The blood type diet does not recommend the traditional calorie counting that is emphasized in most other diets, but rather urges those who are dieting for weight loss to replace foods on the "avoid" list with those that are recommended for their blood type. By replacing foods that do not interact well with your blood type, you can lose weight, or so the diet claims. However, Dr. D'Adamo states that the primary objective of the Blood Type diet is improved health, although weight loss can be an attractive side effect.

Effectiveness and Reviews

• A survey of more than 6,500 users of the blood type diet found found that 71 percent reported some form of health improvement, including weight loss, increased energy and a decreased amount of digestive disorders. However, this study was conducted by the makers of the diet and many health experts are skeptical about Dr. D'Adamo's claims. Juliette Kellow, a registered dietitian, called the diet's theory "nonsense" and argues that there is no scientific evidence that blood type influences how our body digests food. Katherine Zeratsky, a dietitian with the Mayo Clinic, also found that evidence behind the Blood Type diet is lacking. The magazine "Health" urges its readers to skip this diet in favor of other weight loss plans that are proven to work.