Peter J. D'Adamo, ND, the author of Eat Right for Your Type: The Individualized Diet Solution to Staying Healthy, Living Longer & Achieving Your Ideal Weight, believes blood types affect the digestive system and that some foods good for people of one type are "dangerous" for another.
It goes further than that for D'Adamo, a naturopathic doctor, who believes that your blood type also determines your susceptibility to certain illnesses and how you should exercise.
Critics cite a lack of published evidence backing D'Adamo's blood type-based diet plan. "I know of no plausible rationale behind the diet," says John Foreyt, PhD, a researcher at the Baylor College of Medicine in Houston.
This diet may suit those enthusiastic about a plan that doesn't involve tracking calories or fat grams, while others may find it difficult to stay within the diet's confines, a challenge made greater if more than one person in a household follows the diet -- and has a different blood type.
What You Can Eat on This Diet
What you can eat and how you exercise on this diet depends on who you are.
If you're blood type O ("for old," as in humanity's oldest blood line) your digestive tract retains the memory of ancient times, says D'Adamo, so you're metabolism will benefit from lean meats, poultry, and fish. You're advised to restrict grains, breads, and legumes, and to enjoy vigorous exercise.
Type A ("for agrarian") flourishes on vegetarian diets, "the inheritance of their more settled and less warlike farmer ancestors," says D'Adamo. The type A diet contains soy proteins, grains, and organic vegetables and encourages gentle exercise.
The nomadic blood type B has a tolerant digestive system and can enjoy low-fat dairy, meat, and produce but, among other things, should avoid wheat, corn, and lentils, D'Adamo says. If you're type B, it's recommended you exercise moderately.
The "modern" blood type AB has a sensitive digestive tract and should avoid chicken, beef, and pork but enjoy seafood, tofu, dairy, and most produce. The fitness regimen for ABs is calming exercises


































