In the 1930s, dentist Weston Price began taking expeditions around the world and uncovered the link between modern eating habits and chronic degenerative diseases. He also discovered that there wasn’t a single diet that is ideal for everyone due to variation in climate, local produce, environmental conditions, heredity, genetics, and culture.
In later years, George Watson, Roger Williams, William Kelley, and others continued research in this area. They believed that individual metabolism varied greatly due to two factors which were strongly influenced by heredity:
- Autonomic nervous system dominance. One branch of the autonomic nervous system, the sympathetic nervous system, uses energy and is often referred to as the “fight or flight” response. The other branch, the parasympathetic nervous system, conserves energy and helps with the digestion of food. Proponents of the diet believe that one branch tends to be stronger or more dominant than the other.
- Rate of cellular oxidation. This refers to the rate at which cells convert food into energy. According to proponents of the metabolic typing diet, some people are fast oxidizers, who can rapidly convert food into energy. In order to balance their systems, fast oxidizers need to eat heavier proteins and fats that burn slowly. In contrast, slow oxidizers convert food into energy at a slow rate. In order to balance their systems, proponents recommended that they eat mainly carbohydrates rather than protein and fat.
How Can I Find out My Metabolic Type?
In the book The Metabolic Typing Diet, researcher William Wolcott offers a simple home-test to identify one’s metabolic type. For an accurate diagnosis, a trained health practitioner can provide a thorough assessment that may include urine and blood tests. Wolcott provides three general metabolic types:
- Protein types – Protein types are fast oxidizers or parasympathetic dominant. They tend to be frequently hungry, crave fatty, salty foods, fail with low-calorie diets, and tend towards fatigue, anxiety, and nervousness. They are often lethargic or feel “wired”, “on edge”, with superficial energy while being tired underneath.
- Carbo types – Carbo types are slow oxidizers or sympathetic dominant. They generally have relatively weak appetites, a high tolerance for sweets, problems with weight management, “type A” personalities, and are often dependent on caffeine.
- Mixed types – Mixed types are neither fast or slow oxidizers and are neither parasympathetic or sympathetic dominant. They generally have average appetites, cravings for sweets and starchy foods, relatively little trouble with weight control, and tend towards fatigue, anxiety, and nervousness.
According to proponents of the metabolic typing diet, the three metabolic types should eat the following foods:
- Protein types: Diets that are rich in protein, fats, and oils, and high-purine proteins such as organ meats, pate, beef liver, chicken liver, and beef. Carbohydrate intake should be low.
- Carbo types: Diets that are high in carbohydrates and low in protein, fats, and oils. They should eat light, low-purine proteins.
- Mixed types: Diets that are a mixture of high-fat, high-purine proteins and low-fat, low-purine proteins such as cheese, eggs, yogurt, tofu, nuts. This type requires relatively equal ratios of proteins, fats, and carbohydrates.
According to proponents of the diet, the metabolic typing diet takes into account individual dietary preferences, metabolism, and needs, unlike other diets that recommend the same plan for everyone. The metabolic typing theory may help to explain why some people do better on a high protein, low carb diet, while others do better on a high carb diet. Wolcott explains the effects of different popular diets on the metabolic types:
- High Carb, Low Fat Diet – This diet is suitable for carbo types. However, in protein types and mixed types, a high carb, low-fat diet can increase fat storage by increasing insulin, and lower metabolic rate by breaking down muscle tissue due to insufficient protein intake, and may disrupt adrenal and thyroid function.
- High Protein, High Fat Diet (e.g. Atkins Diet, Hamptons Diet) – This diet is suitable for protein types. However, in carbo types and mixed types, a high protein, a high-fat diet can increase fat storage by disturbing cellular oxidation and lower metabolic rate by creating a shortage of glucose caused by low carb intake. It may also disturb adrenal and thyroid function.
- 40-30-30 Diet (e.g. Zone diet) – This diet is suitable for mixed types. However, a 40-30-30 diet can increase fat storage by disturbing oxidation. It can lower metabolic rate by creating a shortage of glucose in carbo types and a shortage of protein in protein types, both resulting in muscle breakdown.
Critics of the metabolic typing diet say that the diet isn’t balanced. Also, a diet rich in organ meats, pate, and saturated animal fats is unhealthy.
If you’re considering trying the diet, make sure to consult your doctor first to discuss the potential risks and benefits.