Perhaps this diet sounds feasible since it mentions one of the body's most basic biological components in its title -- blood. Don't be fooled, though; there's no proof that this diet works [source: Hardy]. To be fair, it hasn't been disproved either. "From my understanding, health and wellness was the primary focus of this diet, and weight loss was a nice side effect, if you're able to master the food restrictions," says Hardy.
The diet is based on the notion that food intake should be determined by blood type (A, vegetarian; B, a balanced omnivore diet; AB, combination of food groups in moderation; or O, high protein), and that food proteins are digested differently depending on these various blood types [source: Lam]. Thereby, health problems can result from eating food that's not well matched to your specific blood type.
In the end, the type of diet that has proven to be the most healthy and reliable requires a combination of eating all the food groups in moderation and frequent, low-impact exercise.