What Is the Metabolic Typing Diet?

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Salting Meat
Salting Meat. JGI/Jamie Grill/Getty Images

The metabolic typing diet is based on the premise that metabolism—the processes the body uses to convert food into energy, like breathing and digesting food—is different for everyone. We each burn calories in our own ways and at our own rates, and those rates can change over time (both short-term and long-term). Proponents of the metabolic typing diet suggest that people can be divided into three different metabolic types, and that they should eat according to those types.

What Experts Say

"The metabolic typing diet maintains that people have different macronutrient needs based on their metabolism. Experts concur that people have individualized nutrition needs, but disagree with the specific metabolic typing personalities and diets, which can be unbalanced."
Chrissy Carroll, RD, MPH

Background

In the 1930s, dentist Weston Price began taking expeditions around the world studying the link between modern eating habits and chronic degenerative diseases. He found 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:

  1. 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.
  2. 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 It Works

In his book "The Metabolic Typing Diet," researcher William Wolcott offers a 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 or 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, and "type A" personalities. They 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.

What to Eat

The three metabolic types have very different lists of recommended foods.

Protein Types

These people need a diet that is rich in oils and high-purine proteins such as organ meats, beef, dark-meat poultry, and seafood including salmon, tuna, herring, and mussels. Protein types can also eat fats such as eggs, whole milk, cream, and whole-milk cheese. Their carbohydrate intake should be low with a focus on complex carbs (whole grains, vegetables) over simple ones (sugary, starchy foods). They should aim for a macronutrient balance of 40 percent protein, 30 percent fats, and 30 percent carbs at each meal.

Carbo Types

These types need a diet that is high in carbohydrates and low in protein, fats, and oils. They should eat low-purine proteins, such as turkey and chicken (light meat only) and lighter fish like haddock, perch, sole, and flounder. Carbo types should stick with low-fat dairy products and eat lots of vegetables, fruits, and whole grains. They don't need to load up on refined carbs. Their ideal macronutrient balance is 60 percent carbs and about 20 percent of both fats and protein.

Mixed Types

People classified as "mixed" types should eat a mixed diet, one that is a mixture of high-fat, high-purine proteins and low-fat, low-purine proteins such as eggs, yogurt, tofu, and nuts. This type requires relatively equal ratios of proteins, fats, and carbohydrates.

Recommended Timing

The diet does not offer much advice on when to eat, but notes that protein types should eat plenty of protein with every meal. Carbo types also probably need protein with each meal, but less of it and from lighter sources (e.g., light meat poultry).

Resources and Tips

"The Metabolic Typing Diet" offers advice on how to determine your metabolic type and eat accordingly. To go even deeper, you can take a detailed online test at a cost of $50, which includes resources such as meal plans along with the results, and/or hire a metabolic typing advisor via Wolcott's website. Wolcott's site also recommends and sells supplements.

Modifications

Wolcott recommends following the diet to the letter in order for it to be effective. However, he also notes that metabolic type can evolve and adjustments will be necessary as the body adapts to a new way of eating.

Note that people with certain medical conditions should use caution. The protein type diet, for example, could be dangerous for people with kidney or heart disease. And people with diabetes need to tailor their carbohydrate intake to their blood sugar needs, not their metabolic type.

Pros and Cons

Pros

  • More individualized than other diets

  • Suggests limiting refined carbs for all types

Cons

  • Macronutrient portions are not balanced

  • Protein type diet is too high in saturated fats

  • No scientific evidence

Pros

Customized

It's true that everyone is different and every body has different needs, so a diet that acknowledges that can be helpful. 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.

Limits Refined Carbohydrates

The diet recommends keeping simple carbs, such as white flours and sugars, to a minimum for all types, which is generally sound advice.

However, much of the other advice in this book is less sound. Be aware of the drawbacks of following this diet.

Cons

Out of Balance

Both the protein type and mixed type eating plans advocate for a macronutrient mix that is not balanced, with too much emphasis on one type of macronutrient (such as protein) at the expense of others.

High in Saturated Fats

A diet rich in organ meats, butter, and red meat, such as the protein type eating plan, is unhealthy. Consuming too much saturated fat can increase the risk of heart disease and stroke and also lead to weight gain.

No Scientific Evidence

The metabolic typing theory is based on anecdotal studies of people and populations. There have not been any clinical trials or other peer-reviewed studies of the theory or the diet that could help support its claims. One tiny 2008 study attempted to correlate the results of the metabolic typing questionnaire found in the book with lab tests of metabolism. It found that the questionnaire "did not accurately reflect the actual metabolic processes in a usable way."

How It Compares

Since the eating plan for each of the three metabolic types is so different, it's difficult to compare the entire metabolic typing diet to other diets. The carbo type plan, for example, provides for a ratio of macronutrients (carbs, proteins, and fats) that meets expert guidelines, while the plans for the other two types are less balanced.

USDA Recommendations

Macronutrients

The USDA suggests fairly broad ranges for macronutrient intake: 10 to 35 percent for protein, 20 to 35 percent for fats (with less than 10 percent saturated fats), and 45 to 65 percent for carbohydrates. On the metabolic typing diet, this means the protein type plan has too much protein and fat and not enough carbs. The carbo type plan (at roughly 20 percent protein, 20 percent fats, and 60 percent carbs) is within the range. And the mixed type is at the high end of the range for both protein and fat and skimps on carbs.

Calories

There is no calorie counting in the metabolic typing diet, which Wolcott cites as a benefit. The theory goes that once you are eating the foods that are right for your type, you will not be hungry between meals or crave unhealthy foods that don't work for your body.

USDA guidelines, however, recommend limiting calories to promote weight loss. Your daily calorie intake target will depend on your age, sex, weight, and activity level. This calculator helps you determine a manageable goal.

Similar Diets

We can compare the eating plan for each metabolic type to another, similar eating plan.

Metabolic Typing Diet

  • Nutritional balance: The amount of protein, fats, and carbohydrates consumed varies greatly among the three types identified in the diet. The protein type eating plan, in particular, likely contains too much protein and fat for most people. All plans suggest limiting refined carbs, which is a healthy choice because these foods tend to be low in useful vitamins and minerals and high in calories.
  • Safety: The protein type diet has too much fat to be healthy for most people.
  • Effectiveness: Although this diet might help some users lose weight, there is no high-quality scientific evidence of the diet's effectiveness.
  • Sustainability: The theory behind this diet suggests it should be used lifelong, as metabolic types are hereditary. Depending on their metabolic type, users might find it challenging to eat the types of food required (although Wolcott says that most people naturally prefer the diet that matches their type).

Atkins Diet

  • Nutritional balance: The Atkins diet is a phased low carb, high protein, high fat eating plan. It is similar to the protein type diet recommended by the metabolic typing diet and allows for just 10 to 25 percent of calories to come from carbohydrates (depending on the phase).
  • Safety: This diet places limits on fruits, vegetables, and whole grains, all of which contain important nutrients. It is too restrictive to be used for any length of time (the induction, or first phase, is only two weeks long).
  • Effectiveness: Many people do lose weight on the Atkins diet, especially at first. Maintaining that weight loss takes work and continued limits on carb intake.
  • Sustainability: The Atkins diet does have a maintenance phase, but users may find they have to restart the diet from time to time in order to prevent weight gain.

Ornish Diet

  • Nutritional balance: The Ornish diet (particularly in the "prevention" version) is a higher carb, lower fat plan, similar to the carbo type eating plan on the metabolic typing diet. Both call for 60 percent of calories to come from carbohydrates.
  • Safety: This is a safe eating plan that may even have benefits for heart health.
  • Effectiveness: Because it limits calories and fat, this diet will help most followers lose weight.
  • Sustainability: It can be challenging to adhere to a plan like this that is quite low in fat and mostly vegetarian.

Zone Diet

  • Nutritional balance: The Zone diet is a lower-carb eating plan that is similar to the mixed metabolic type diet. The Zone recommends a daily balance of 40 percent of calories from carbs, 30 percent from fat, and 30 percent from protein (for the mixed type, it's roughly 30 to 35 percent from each group).
  • Safety: This diet is healthy although it is quite low in calories and can be low in fiber and certain vitamins.
  • Effectiveness: Like other eating plans that restrict certain types of food, this diet could help some people lose weight. But studies haven't shown it to be especially effective.
  • Sustainability: Although no foods are off-limits, many are discouraged. And portions and overall calorie count are low. These factors could make it hard for many people to stick with this way of eating.

A Word From Verywell

If you're considering trying the metabolic typing diet, consult your doctor first to discuss the potential risks and benefits. It's unclear how accurate customized metabolic types are, and the best diet is one that is truly personalized for you and your needs, including any medical conditions you may have. Your physician or a dietitian can help you develop a plan tailor-made for you.

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Article Sources

Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Heart Association. Saturated Fat.

  2. Clarke D, Edgar D, Higgins S, Braakhuis A. Physiological analysis of the metabolic typing diet in professional rugby union players. NZ J Sports Med. 2008;35(2):42-47.

  3. U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015 – 2020 Dietary Guidelines for Americans. 8th Edition.

Additional Reading

  • Wolcott W, Fahey T. The Metabolic Typing Diet. Broadway Books, New York. 2000.