By Peter J. D'Adamo, nD, with Catherine Whitney
This weight loss plan, often referred to as the blood-type diet, proposes that a person should eat according to the foods that were common during the time in history when her specific blood type evolved. Those with the oldest, type O, for instance, are advised to consume the foods of ancient hunter-gatherers, while people with type A, which surfaced in the first agrarian era, should be largely vegetarian. D'Adamo, a naturopathic physician, cites some research (including his own and his father's) to support the assertion that individual blood types have different chemical reactions to the same foods and that this can affect weight gain. To help his readers find the right balance, D'Adamo divides food into three categories for each blood type—the highly beneficial, the neutral, and items to avoid.
What the experts like: The foods suggested in the individual diets are basically healthy. "In the end," Nelson says, "it's about cutting out the junk and eating whole foods." In fact, says Perry-Bottinger, "what he's recommending for each blood type is good for every blood type."
What they don't like: D'Adamo may tout his sources, but Lash concludes, "there's no scientific evidence to support what's in Eat Right for Your Type. It's silly. You can get equally good dietary advice by reading your horoscope." Economos agrees, saying "there's no randomized clinical trial to show that anyone who eats a diet based on his or her blood type is successful." And both she and Perry-Bottinger worry that D'Adamo's theories will prevent some people from eating foods, such as avocado, tofu, and legumes, that have been shown to be beneficial to just about everyone.
Crunching the numbers: Those with type B blood are allowed the most calories per day, at roughly 1,750, and type A the fewest, with less than 1,200. The type O plan is low in fiber, iron, calcium, and vitamins D and E, and high in cholesterol. The type A plan is also low in fiber and iron as well as vitamins E and D. Type AB is low in fiber, folate, vitamin E, calcium, magnesium, and zinc. Type B has the fewest deficiencies, but it is lacking in vitamin E and iron.