J.Y. Chia has only good things to say about the blood type diet.

"I would credit the boost of energy as the biggest gift that I can get from the blood type diet as I can accomplish the goals that I set for the day," Chia, 21, says.

The blood type diet, founded by Dr. James D'Adamo, requires a diet of certain foods and even an exercise regimen based on blood type. It is also referred to as the D'Adamo Diet.

Although the diet helps many lose weight, Chia, who has type O blood, says her motivation was to boost her energy level. She has been following it for about a year.

"It took awhile for me to give this diet a shot. as I am skeptical about it," she says. "The large motivation came when I was getting fatigue easily and there wasn't enough energy to get me by to do the things that I needed to accomplish." She admits that initially the experience was not easy.

"During the first week of testing out the diet, there were some challenges, as some foods that I like are out of bound in the blood type diet," Chia says. "However, weeks became months. It is a generally pleasant experience for me as I feel more energetic when I abstain from pork, which is a meat type Os should avoid, and also by minimizing wheat intake."

D'Adamo, author of The D'Adamo Diet and founder of the D'Adamo Institute for natural therapies, believes that people should follow a diet based on blood type. The D'Adamo Institute seeks to understand the unique characteristics of each person using naturopathic medicine.

What To Eat

Type As should not eat meat, dairy products or whole-wheat products. A vegetarian diet is best for this blood type. D'Adamo says.

Type Os should eat protein, meat and dairy products.

Type Bs mix should mix dietary requirements of both A and O blood types, which would be a combination of meat and plenty of vegetables.

As for exercise regimens, Type As are told to look for less rigorous activities such as yoga or Tai Chi. Type Bs should follow an exercise regimen that includes yoga or Tai Chi as well as 2-mile run. Type Os require rigorous exercise.

D'Adamo says the diet will help deal with health issues such as hypoglycemia, hormonal imbalances and irregular bowel movements. He says this is key, because when the one organ is not working properly it causes other organs to work extra hard.

"Conditions such as hyperactivity, inability to concentrate, loss of memory and irritability are often caused by this problem. Hypoglycemia is the No. 1 disease of this generation primarily because of our inordinate consumption of refined and processed foods," D'Adamo writes.

D'Adamo says that this must be addressed before any real weight loss can be attained. For an O, it typically takes 2 years; 2½ for a B and 3 years for an A.

Dealing with being overweight is crucial, D'Adamo says, because weight problems often lead to diabetes, heart disease and kidney problems.

No Science

Tara Gidus, a registered dietician and nutritionist, says it is definitely true that some people may have to modify diet's based on medical condition, but not enough research has been done to show a direct correlation to blood type.

"There's no medical evidence to show that your blood type should determine what you eat," Gidus says.

Gidus believes there is some good dietary information in the book, such as limiting portion sizes and incorporating a more balanced meal.

"I don't think it's off the wall eliminating foods, but there's no medical research to back it up," she says.