Betty, I agree with Todd's logic regarding chaos theory. This is why I suggested taking supplements and modifying intake of certain paleo foods. If you have an under lying metabolic problem, i.e. hypercholesterolemia, insulin resistance, diabetes, hypertension, obesity, etc., then you need to "compensate" for this condition. Simply returning to "initial conditions" will usually not be enough to correct the disease. I am only superfically aware of the blood type theories. However, I have several problems with this theory: (1) It's recommended that Type A's be vegetarian or greatly reduce meat intake (lower gastric acid and enzymes). It also states that Type A was the first blood type variation after Type O. If this is the case, why would Type A, for all practical purposes, be totally opposite of Type O (high gastric acids and enzymes) in eating requirements? It seems there should be a more gradual evolution to being able to eat certain foods. (2) From data that I've seen, the Type A blood type began to appear between 10-20 thousand years ago. If this is the case, this predates the agricultural revolution, which usually is placed at 10 thousand years ago in the Middle East, much later in Europe. Why would a blood type that is adapted to agricultural foods appear either before or at the same time as the neolithic period? Before looking at blood type, I would focus on current medical conditions, and family history. If your family has any history of obesity, heart disease, diabetes (all signs of insulin resistance), eating a high carb or vegetarian diet may aggravate the problem, irregardless of blood type. Ed Campbell, DC,CSCS