Metabolic Typing is a fusion of two system of metabolic analysis: the Oxidative (or energy generating) and the Autonomic (or energy regulating). The basic premise is that one or the other of these two systems (the Oxidative or the Autonomic) will be more dominant in controlling any given person's metabolism. Metabolic Typing seeks to identify: 1) which system is dominant in any given individual; and 2) which of two sub-types within that system characterizes the individual (Fast or Slow Oxidizer within the Oxidative system, and Sympathetic or Parasympathetic within the Autonomic system).

The reason that it is important to know the dominance system is that foods have opposite pH effects in members of the two dominance systems; e.g. foods that acidify the two Oxidizers (Fast or Slow Oxidizers) will typically alkalize the two Autonomics (Sympathetics or Parasympathetics), and vice versa. Acidifying the Oxidizers is desirable for the overly alkaline Slow Oxidizer, but contraindicated for the overly acid Fast Oxidizer. Conversely, alkalizing the Autonomics is desirable for the overly acid Sympathetic, but undesirable for the overly alkaline Parasympathetic.

The importance of determining Oxidative or Autonomic dominance is that most foods and supplements are processed differently in each system, producing a different net pH effect at the level of the blood. For example, fruits and vegetables are generally considered to be alkaline forming, and so indeed most of them are within the Autonomic system; but within the Oxidative system they have precisely the opposite effect, and are generally acid forming. Conversely, protein foods are generally considered to be acid forming, and while most of them are indeed acid forming within the Autonomic system, they are actually alkaline forming within the Oxidative system. Because one member of each dominance system (the Fast Oxidizer and the Sympathetic) already tends towards a relatively acid blood pH, feeding them foods that further acidify their blood would be counterproductive. Conversely, feeding alkaline forming foods to the two types that already run on the alkaline side (the Slow Oxidizer and the Parasympathetic) would also be counterproductive. But, given that foods that are acid forming in one dominance system are alkaline forming in the other system, we end up with two types with opposite blood pHs — one from each dominance system — sharing the same nutritional requirements.

Thus, what we refer to as the Group I diet — lower in protein and fat, and higher in complex carbohydrates — is shared by the overly alkaline Slow Oxidizer and the overly acidic Sympathetic. Because the same foods have opposite pH effects in members of the two dominance systems, the Group I foods acidify the overly alkaline Slow Oxidizer while alkalizing the overly acid Sympathetic, thereby helping to move both types towards a balance point, albeit from opposite directions. Similarly, the Group II diet — higher in protein and fat, and lower in complex carbohydrates — helps to alkalize the overly acidic Fast Oxidizer and acidify the overly alkaline Parasympathetic. Thus, from a Metabolic Typing perspective, the net pH effect of any given food is not fixed, as is usually assumed, but is determined to a large extent by the particular metabolism (or, more accurately, by which dominance system controls the metabolism) of the individual consuming it.

After identifying the correct dominance system and Metabolic Type, the Metabolic Typing practitioner uses dietary modification to optimize blood pH and balance the individual’s metabolism, thereby improving energy levels, stabilizing weight, and helping the body become more resistant to disease.