By Cathy Wong | Updated on February 03, 2020

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.

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.

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.3 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.3 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.