Weight Loss & Diet Plans

Food for Your Blood?

The Diet's Theory continued...

D'Adamo also theorizes that a person's ability to digest foods varies depending on blood type. For instance, he claims that Type O's can efficiently digest meats because they tend to have high levels of stomach acid. Type A's, he says, have low stomach acid and store meat as fat.

D'Adamo bases his theories on research he's conducted since the early 1990s on the connections among blood type, food, and disease. He says his research builds on work done by his father, a naturopathic physician who drew on his observations of his patients. Based on those observations, D'Adamo also suggests that type O's should exercise vigorously, B's moderately, and A's gently. AB's, he says, need calming exercise.

Where's the Beef?

While D'Adamo acknowledges that there is no scientific study that demonstrates that his program helps with weight loss or disease prevention, he has posted 52 pages of references on his web site (www.dadamo.com) that he says back up his belief that blood type may be related to disease. But many mainstream nutritionists and medical doctors roundly criticize the program and urge their patients not to follow it. These critics cite the lack of published studies showing that the diet works.

"My initial skepticism of the diet plan was supported by the complete lack of scientific foundation [in D'Adamo's book]," says John McMahon, ND, a naturopathic physician in Wilton, Conn. "I believe he feels he is doing people a favor, but I think he is seriously mistaken."

Adds John Foreyt, PhD, a weight loss researcher at the Baylor College of Medicine in Houston: "I know of no plausible rationale behind the diet."

Critics also quibble with D'Adamo's theory that there is an association between certain blood types and specific diseases (which he says can be tempered by eating certain foods). Though this theory has long been talked about and investigated, no conclusions have been reached, says Andrea Wiley, PhD, an associate professor of anthropology at James Madison University in Harrisonburg, Va. It would be a huge leap, she adds, to say with certainty that a person with a specific blood type will probably contract a specific disease -- as D'Adamo claims when justifying his diet.

Potential for Harm?

In fact, some experts go so far as to say the diet may be harmful. Michael Klaper, MD, a general practice physician in Pukalani, Hawaii, says eating large quantities of meat, for instance, is discouraged by most diet plans, because the fat can add up and it may leave you too full to eat other crucial foods. In another example, a lactose-intolerant Type B, who would be encouraged by D'Adamo's plan to eat a variety of dairy foods, would have significant difficulties, Klaper says.