STAMFORD, Connecticut (CNN) — Every time we pick up a fork, it seems, a new diet book tells us to cut back, or load up, on one food or another. Now, two new books argue that obesity and other medical problems can be tackled with a diet based on blood type.
"Your Body Knows Best," by Ann Louise Gittleman, pitches personalized eating plans based on one's metabolic rate, ethnic ancestry and blood type. Dr. Peter D'Adamo, a naturopathic specialist, takes a similar approach in his book "Eat Right 4 Your Type."
"[Blood types] control whether we view certain things in our diet as foreign or friendly," D'Adamo told CNN.
But skeptSTM, including Dr. Victor Herbert, call theories linking blood type and diet "pure horse manure." Blood type has "nothing to do with ... how we handle the food we eat," says Herbert, who studies blood and nutrition at New York's Mt. Sinai Medical Center.
Responding to the criticism, D'Adamo says, "All ideas that are revolutionary are going to engender opposition ... because they are very threatening."
Theory: Best diet depends on blood type
D'Adamo's ideas are based on evidence that the most common blood type, "O," goes back to the pre-historic age of hunter-gatherers. As a result, the theory goes, people today with type "O" blood do best eating foods rich in fat and protein.
Type "A" blood appeared later in farming cultures, making modern-day "A" and "A-B" blood types better off with diets heavy on grains and carbohydrates.
Blood type "B," evolved after "O" and "A" and is a balance of both, says D'Adamo.
Under his theory, a person with type "B" blood can't burn the fat in red meat as efficiently as a type "O" can. Likewise, a type "B" person doesn't burn carbohydrates as fast as a type "A" does.
It worked — for him
That made sense to Michael Kirshbaum, who went to Dr. D'Adamo three years ago with a chronic liver condition he says his doctors couldn't relieve. "I had itching throughout my body such that I was scratching my skin off just about everywhere," said Kirshbaum, who has type "B" blood.
D'Adamo gave him five herbal medicines and told Kirshbaum to stop eating potatoes, wheat products, chicken and oranges. Now Kirshbaum and his wife, Regina — also a type "B" — feast on fish, rice, beef vegetables and fruit. The satisfied patient says critSTM of blood type diets should "try it and find out how much healthier they feel and how much healthier they become." 
