What Is the Metabolic Typing Diet?

Metabolic diet

Verywell / Debbie Burkhoff 

At Verywell, we believe there is no one-size-fits-all approach to a healthy lifestyle. Successful eating plans need to be individualized and take the whole person into consideration. Prior to starting a new diet plan, consult with your healthcare provider or a registered dietitian, especially if you have an underlying health condition.

The Metabolic Typing diet is based on the concept that metabolism—the processes the body uses to convert food into energy, like breathing and digesting food—is different for everyone. It was introduced as a weight-loss plan in 2001 with the publication of the book, "The Metabolic Typing Diet," by researcher William Wolcott and science writer Trish Fahey. Wolcott is regarded as a pioneer in metabolic research and a leading expert in metabolic typing.

The concept of metabolic typing dates back to the 1930s when Weston Price, a Canadian dentist, traveled around the world to study the link between modern eating habits and chronic degenerative diseases. He found that there wasn't a single diet that was ideal for everyone due to variation in climate, local produce, environmental conditions, heredity, genetics, and culture.

In later years, researchers George Watson, Roger Williams, William Kelley, and others continued to study this idea. Wolcott's study eventually led to a theory that an individual's metabolism varied due to two factors, which are influenced by heredity:

  • Autonomic nervous system dominance: The energy-burning sympathetic nervous system is referred to as the fight-or-flight response. Its opposing energy-conservation branch, the parasympathetic nervous system, supports rest and digestion. Proponents of metabolic typing believe that one branch is more dominant than the other in most people.
  • Rate of cellular oxidation: Cells convert food into energy (oxidizing it) at certain rates. According to proponents, some people are fast oxidizers who need to eat heavier proteins and fats that burn slowly. By contrast, slow oxidizers are advised to eat mainly faster-digesting carbohydrates rather than protein and fat.

The premise of "The Metabolic Typing Diet" book is that there is no single diet that works for everyone. The diet suggests that people can be divided into three different metabolic types and that they should eat according to those types. While most people can agree that everyone burns calories at different rates and that a balanced diet ought to be tailored to suit an individual's needs, scientific evidence for the Metabolic Typing diet is still lacking.

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

What Can You Eat?

"The Metabolic Typing Diet" book offers a troubleshooting test to help you identify your metabolic type. (For a more accurate diagnosis, a trained health practitioner can provide a thorough assessment that may include urine and blood tests.) Your results from this test will indicate that you fall into one of the three metabolic types:

  • Carbo: 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.
  • Protein: 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 toward fatigue, anxiety, and nervousness. They are often lethargic or feel wired or on edge with superficial energy while being tired underneath.
  • Mixed: Mixed types are neither fast nor slow oxidizers and are neither parasympathetic nor sympathetic dominant. They generally have average appetites, cravings for sweets and starchy foods, relatively little trouble with weight management, and tend toward fatigue, anxiety, and nervousness.

What You Need to Know

According to Wolcott, the Metabolic Typing diet should be adhered to for life, as metabolic types are hereditary. The caveat is that your metabolic type can evolve over time, which means you'll have to make changes to your diet plan along the way. Remember that while the diet might help some people to lose weight, there is no high-quality scientific evidence to support the program's effectiveness.

The program does not offer much advice on when to eat, but Wolcott recommends following the diet exactly as directed in the book in order for it to be effective. Those interested in learning more can also take a comprehensive online test for $50, which includes additional resources such as meal plans to accompany the results. You can also hire a Metabolic Typing advisor via the Metabolic Typing website, which also recommends and sells supplements.

What to Eat
  • Carbo types: mostly complex carbs like whole grains, with smaller amounts of lighter, lean protein (chicken, turkey seafood), and fats

  • Protein types: mostly high-purine protein (organ meats, beef, dark-meat poultry) and fats with smaller amounts of complex carbs

  • Mixed types: equal amounts of protein, fats, and complex carbohydrates

What Not to Eat
  • All three types limit refined carbohydrates and added sugars

Each of the three metabolic types identified in this plan has its own guidelines for macronutrient ratios and a different list for recommended foods. Here's a closer look at the ratios for the three metabolic types and what you can eat on each plan:

Carbo Types

This metabolic group requires a diet high in carbohydrates and low in protein, fats, and oils. The carbo type diet provides for a ratio of macronutrients—60% carbs and about 20% of both fats and protein. It resembles the Ornish diet, as it is a higher carb, lower fat plan.

Carbo types should try to eat protein with each meal, but less of it. They should emphasize low-purine proteins such as turkey and white meat chicken, and lighter fish like haddock, perch, sole, and flounder. They should also stick with low-fat dairy products and eat lots of vegetables, fruits, and whole grains. They should not load up on refined carbohydrates, however.

Protein Types

The protein type diet is reminiscent of the Atkins diet (depending on the phase) in that it only allows for about 20–100 grams of net carbohydrates. This high-protein group should eat plenty of protein with every meal, aiming for a macronutrient ratio of 40% protein, 30% fats, and 30% carbs. According to nutrition experts, this is likely too much protein and fat for most people.

They require a diet 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. Carbohydrate intake should be low with a focus on complex carbs (whole grains, vegetables) over simple ones (sugary, starchy foods).

Mixed Types

The mixed metabolic diet may remind you of the Zone diet as it is a lower-carb eating plan. This type requires relatively equal ratios of proteins, fats, and carbohydrates, which nutrition experts say is still too high in protein and fat.

People classified as "mixed" types should therefore follow a mixed diet that includes high-fat, high-purine proteins as well as low-fat, low-purine proteins like eggs, yogurt, tofu, and nuts, in addition to complex carbohydrates.

People with certain medical conditions should consult their healthcare provider before trying this diet. The protein plan could be dangerous for those with kidney or heart disease if they're getting too much protein from meat versus plants. And people with diabetes should 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

Proponents of the Metabolic Typing diet appreciate the customization aspect of the program. Everyone is different and has different needs, so a diet that acknowledges this can be helpful. Depending on an individual's metabolic type, however, some people may find it difficult to eat the types of food required (but Wolcott says that most people naturally prefer the diet that matches their type).

All three metabolic diet plans limit refined carbohydrates and recommend keeping simple carbs such as white flour and sugar to a minimum, which is nutritionally sound advice. Still, there are drawbacks to this program.

For instance, a diet rich in organ meats, butter, and red meat, such as the protein type eating plan, is not healthy or sustainable long term. Additionally, 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.

Despite that Wolcott is an expert in the field of metabolic typing research, the Metabolic Typing diet itself lacks large-scale, peer-reviewed evidence to prove that it is an effective weight-loss plan.

Is the Metabolic Typing Diet a Healthy Choice for You?

Current dietary guidelines set forth by the U.S. Department of Agriculture recommend consuming a variety of nutrient-dense foods including:

  • Vegetables of all types—dark, leafy greens; red and orange; beans, peas, and lentils; starchy; and other vegetables
  • Fruits, especially whole fruit
  • Grains, at least half of which are whole grains
  • Dairy, including fat-free or low-fat milk, yogurt, and cheese, and/or lactose-free versions and fortified soy beverages and yogurt as alternatives
  • Protein foods, including lean meats, poultry, and eggs; seafood; beans, peas, and lentils; and nuts, seeds, and soy products
  • Oils, including vegetable oils and oils in food such as seafood and nuts

The USDA suggests fairly broad ranges for macronutrient intake: 10–35% for protein, 20–35% for fats (with less than 10% saturated fats), and 45–65% for carbohydrates.

With federal guidelines in mind, the protein type plan on the Metabolic Typing diet suggests too much protein and fat and not enough carbohydrates. The carbo type plan (roughly 20% protein, 20% fats, and 60% carbs) falls within the recommended range. And the mixed type is at the high end of the spectrum for both protein and fat but is lower in carbs when compared to expert advice.

USDA guidelines also recommend monitoring caloric intake to help promote weight loss. But there is no calorie counting in the Metabolic Typing diet, which Wolcott says is a benefit of the program. The idea, according to Wolcott, is 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 aren't good for your body, which would mean there's no need to count calories.

Still, nutrition experts agree that calorie counting is a best practice for weight loss. An individual's daily calorie intake varies depending on age, sex, weight, and activity level. Use this calculator to help you determine the right number of calories to meet your goals.

The three plans on the Metabolic Typing diet are imbalanced, lack scientific evidence, and fall short of federal dietary guidelines for a healthy diet.

Health Benefits

The Metabolic Typing diet takes into account an individual's dietary preferences, metabolism, and needs, unlike many other diet plans. All three types suggest limiting refined carbs, which is a healthy choice since these foods tend to be high in calories, lack vitamins and minerals, and can cause blood sugar to spike.

While following a suggested metabolic diet could help you make healthy dietary and lifestyle changes to promote weight loss, keep in mind that evidence about the Metabolic Typing diet is still lacking. For instance, a 2008 study compared the results of the Metabolic Typing diet questionnaire with metabolism lab tests but states that it "did not accurately reflect the actual metabolic processes in a usable way." 

Health Risks

According to the American Heart Association, consuming too many foods high in saturated fats can increase the risk of heart disease and stroke and also lead to weight gain, which could make the protein diet type plan problematic. Additionally, the plans for both the carbo and mixed types lack balance.

Not getting enough nutrition can cause dizziness and fatigue and also contribute to long-term health problems including high blood pressure, high cholesterol, osteoporosis, and other chronic diseases. Certain dietary imbalances may also lead to obesity and type 2 diabetes.

Despite that evidence on the Metabolic Typing diet is lacking, emerging research shows promise for "metabotyping," a more general term for a personalized nutrition program, as a preventative measure for cardiometabolic disease, which includes heart disease, type 2 diabetes, and kidney failure.

A Word From Verywell

If you're considering trying the Metabolic Typing diet, consult with your doctor or a registered dietitian or nutritionist to discuss the potential risks and benefits. It's unclear as to how accurate the three customized metabolic diet types are and more research is still needed. Your physician or a dietitian can help you develop a plan tailormade just for you.

Remember, following a long-term or short-term diet may not be necessary for you and many diets out there simply don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, budget, and goals.

If your goal is weight loss, remember that losing weight isn’t necessarily the same as being your healthiest self, and there are many other ways to pursue health. Exercise, sleep, and other lifestyle factors also play a major role in your overall health. The best diet is always the one that is balanced and fits your lifestyle.

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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 process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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