What is the Blood Type Diet?
Eat Right For Your Type is a diet based on the theory that the optimal way to lose weight is eating for blood type. Written by Dr. Peter D'Adamo, this book recommends different diets depending your blood type claiming "one man's food may be another man's poison."
How does the Blood Type Diet work?
Specific foods are listed for each blood type with some differences for those who are secretors (meaning people who secrete antigens in fluids such as saliva, sweat or tears). If you don't know your blood type or if you are a secretor, the web site sells those tests, along with a plethora of other blood-type specific products.
D'Adamo believes the blood groups evolved differently giving them a need for different diets. Most people are Type Os and are the hunters giving them a need for red meat and vigorous exercise. Type As are more plant-based, type Bs a mix between O and A. ABs are a mix between type A and type B.
Blood type AB people are told to avoid beef, A types are also to avoid beef; B types are told beef is neutral choice; and O types are told beef is beneficial. All types are told to avoid pork products while lettuce is considered neutral or beneficial.
What does research say?
There are no controlled long-term studies that specifically show that people with this specific blood type who followed this diet lost more weight than those who did not. D'Adamo's site offers data that was self-reported from dieters and collected over the internet showing weight loss results. Also D'Adamo takes pains to address his critics.
Newsweek did an informative article that includes this diet and others that hold similar theories. The article includes an expert's conclusion that "Someday we may know how to tailor a diet to an individual's genetic makeup," says Bonnie Liebman, a nutritionist with the Center for Science in the Public Interest, "but we're not even close."