This is a diet I am questioned about pretty often. Here are a couple of good links that explain the reasoning behind the diet as well as why it is…well, bogus.
Basically the diet claims that prehistorically, our ancestors ate by their blood type. There is absolutely no evidence that this is the case, or that it would help anyone lose weight. For example, if you are “O” blood type, your ancestors were carnivores and so you should avoid any plant based foods and eat only meat.
You will notice in this diet, that calories are also very low. We know that to lose weight you have to eat less than you burn. So, if you are eating less calories, you will lose weight. That is probably the benefit that people see, not eating or avoiding certain foods.
I actually find it very unethical and irresponsible to make claims that go against good sound nutritional research. I had a colleague who had a client that was following the blood type diet. Her blood type was “O” so she gave up fruits, vegetables, beans and grains. She had an increase in her lipid profiles including blood cholesterol and a rise in blood pressure.
It all goes back to eating less calories, moving more and focusing on fruits, vegetables, whole grains and lean proteins.
Emily Fonnesbeck RD,CD