Do you find you’re sluggish after a high-carb meal, but feel amazing after eating a big steak topped with butter?
Maybe you have a vegetarian friend who’s just the opposite — meat makes them feel awful, but they stay fit and energetic on whole grains, beans, and potatoes.
Perhaps yet another friend can go either way — it seems like they eat whatever they want and do just fine.
Nutrition seems to vary broadly from person to person, which begs the question: how much of healthy eating is individual?
That’s the question that metabolic type dieting claims to answer.
Metabolic type dieting (also called metabolic typing) is based on the idea that your metabolism — the way your body turns food into energy — is unique to you.
According to metabolic typing, you fall into one of three categories. You could be carb-efficient, built to run on grains and starches. Or you could be fat-protein efficient — you feel best when you eat plenty of fatty meat. Finally, you could have a mixed metabolism, meaning you do well with a balance of fat, carbs, and protein.
Metabolic type dieting claims that it can help you figure out how your metabolism works, and that if you eat according to your category, you’ll be healthier and will feel better.
This article will cover the theory behind metabolic type dieting, pros and cons of metabolic typing, and how to find your metabolic type, as well as a fat-protein efficient meal plan, carbohydrate efficient meal plan, and mixed type meal plan.
The Theory Behind Metabolic Type Dieting
The theory behind metabolic type dieting began in the 1930s. It was based on a paper written by Weston A. Price, a Canadian dentist and founder of Canada’s National Dental Association.
Throughout his years of dentistry, Price saw more and more patients come in with cavities and gum disease. He began to suspect what we now know is true: diet plays a significant role in dental health.
Price became fascinated by the connection between nutrition and tooth decay. He decided to travel around the world, studying the diets and dental health of remote cultures.
In 1939, Price summed up his travels in a research paper called Nutrition and Physical Degeneration: A Comparison of Primitive and Modern Diets and Their Effects[*]. He concluded that people all over the world were thriving on a wide variety of diets, and that a diet’s impact on health depends on genetics, local environment, climate, and even culture.
In the 1970s, other researchers began expanding on Price’s ideas. They theorized that metabolism varies from person to person, and that each individual person’s metabolism depends largely on two factors:
1. Autonomic Nervous System Dominance
Your autonomic nervous system controls many of your background bodily functions: blood flow, breathing, heartbeat, digestion, and so on. It’s divided into two branches:
- Your sympathetic nervous system, which increases blood flow, heart rate, alertness, and adrenaline release in response to stress (your “fight or flight” response).
- Your parasympathetic nervous system, which calms things back down, returns you to baseline, and, when you aren’t stressed or in danger, controls digestion.
People who support a metabolic typing diet believe that, due to your parents’ genetics, your autonomic nervous system has one branch that’s stronger than the other. They claim that you digest and metabolize food differently depending on which branch of your nervous system is dominant.
2. Rate of Cellular Oxidation
Cellular oxidation is the process your cells use to turn food into energy. Your cells have different processes for breaking down fat, carbs, and protein.
Metabolic type dieters propose that some people oxidize food more quickly. They’re called fast oxidizers, and in theory, they’re healthier when they eat slow-digesting foods like animal protein and fat.
On the other hand, slow oxidizers have a slower metabolism and do better when they eat lots of fast-burning carbohydrates and less protein and fat.
How to Find out Your Metabolic Type
You can take a free metabolic type quiz online. These quizzes usually ask you questions about your hunger levels, the types of food you crave, your personality, and the health issues you struggle with, then use your responses to assign you a metabolic type.
Doctors and nutritionists who support metabolic typing may suggest you take blood or urine tests to figure out your metabolic type. They’ll often analyze your hormones, cholesterol levels, triglycerides, blood sugar levels, and other aspects of metabolic health. Some people also recommend measuring your blood pH.
It’s worth mentioning that there’s no established set of tests or test criteria to figure out your metabolic type. The method varies depending on the online test you take, or on the doctor/nutritionist you see.
The 3 Different Metabolic Types
The metabolic type diet proposes that people fall into one of three different metabolic types, depending on their unique genetics and how their body processes food.
The three metabolic types are:
1. Fat-Protein Efficient Metabolism
Fat-protein efficient body types have high cellular oxidation and are parasympathetic dominant, meaning they burn through food fast and have strong appetites.
If you’re fat-protein efficient, you get hungry every couple hours, especially when you eat carbs.
You crave salty, fatty foods more than you crave sweets (e.g., you want nachos or fries, not gummy bears). You also tend to eat a lot of food, which makes it challenging to follow low-calorie diets. You may struggle with fatigue and anxiety.
In theory, a lot of the fatigue, anxiety, weight gain, and cravings that fat-protein efficient types experience stems from eating the wrong kind of food. They burn through carbs too quickly, which leaves them hungry, tired, anxious, and irritable.
If you’re fat-protein efficient, you should prioritize salty, fatty, high-protein, low-carb food. A sample meal might be a heavily salted ribeye steak with bacon-avocado-ranch salad on the side.
2. Carbohydrate Efficient Metabolism
Carbohydrate efficient types have slow cellular oxidation and are sympathetic dominant, meaning they burn through food slowly and have light appetites.
If you’re carbohydrate efficient, you don’t get hungry too often and tend to be a fairly light eater.
When you do get hungry, though, you crave sugar above all else. You tend toward candy and desserts, and can struggle to stay at a healthy weight. You may also be dependent on caffeine or other stimulants and have a more goal-oriented, type-A personality.
The theory is that carbohydrate efficient people crave sweets and depend on stimulants because their body wants high-quality carbs — whole grains, starchy vegetables, and so on.
If you’re carbohydrate efficient, you should prioritize quality low-fat carb sources, and you should get your protein from chicken or fish instead of heavy red meat. A sample meal might be grilled chicken breast with wild rice, mushrooms, and spinach.
3. Mixed Metabolism
Mixed metabolism types have neither fast nor slow cellular oxidation, and aren’t dominant in either branch of their nervous system. Under the metabolic type theory, this means they can process fat, carbs, and protein equally well and have average appetites.
If you have a mixed metabolic type, you don’t get hungry too often. You may crave both sweet and salty or fatty foods, and you typically don’t have an issue with your weight. You may get anxious or fatigued if you eat too much fat and protein or too many carbs.
Mixed metabolism people do well with a balance of macronutrients (fat, protein, and carbs). A sample meal might be salmon with butter sauce, roasted potatoes, and a side of broccoli.
Pros and Cons of the Metabolic Type Diet
Metabolic typing comes with both pros and cons.
Pros of Metabolic Typing
Regardless of which type you are, metabolic typing recommends a whole-food-based diet that is high in vegetables and low in processed snacks and refined sugars. That’s solid dietary advice.
The metabolic type diet also claims that there’s no one-size-fits-all approach to nutrition, and that you should look at nutrition as an individual.
Again, that’s a good stance to take. There are a lot of different ways to eat that can be good for you. For example, research shows that a ketogenic diet and a flexitarian diet both lead to significant health gains[*][*], despite being very different in their approach to eating.
Metabolic typing encourages you to find something that works for you, which is an excellent way to view nutrition.
But while metabolic typing has a few positives, other parts of it are less convincing.
Cons of Metabolic Typing
The major con of the metabolic type diet is that there’s no scientific research to back it up. There have been no clinical trials supporting the idea of three distinct metabolic types.
There’s also little to no evidence for the theory behind metabolic typing — that your metabolism depends on your nervous system and how quickly your cells oxidize food.
So far, there’s been only one published study on metabolic typing. It compared participants’ metabolic type, which they were assigned based on a questionnaire, to actual metabolic lab tests.
There was no correlation between the participants’ supposed metabolic type and what lab tests showed about their metabolism. The researchers concluded that metabolic type testing is not a valid way to figure out your nutritional needs[*].
What to Eat for Your Metabolic Type
Most nutrition experts agree that metabolic typing is inaccurate. It doesn’t seem to match up with what’s actually happening in your boy.
However, there is value in trying a few different diets to see which one works best for you, and while its theory may be flawed, metabolic typing does lay out three healthy ways to eat.
If you decide to try metabolic typing, these three food lists can help you figure out what foods to include in your diet.
1. Fat-Protein Efficient Foods
This diet is similar to keto or other low-carb diets. Aim for the following macronutrient ratio, broken down by calories:
- 60% fat
- 30% protein
- 10% carbohydrates
Foods that fit into a fat-protein efficient diet include:
- Red meat
- Fatty fish (salmon, mackerel, etc.)
- Dairy (butter cheese, cream, whey protein)
- Full-fat yogurt
- Oils (olive, MCT, coconut)
- Low-carb greens (spinach, broccoli, etc.)
- Low-sugar fruits (blueberry, strawberry, raspberry, blackberry, etc.)
2. Carbohydrate Efficient Foods
This diet is similar to flexitarian and other low-fat, mixed plant diets. Aim for the following macronutrient ratio, broken down by calories:
- 10% fat
- 20% protein
- 70% carbs
Foods that fit into a carbohydrate efficient diet include:
- Lean chicken
- White fish
- Whole wheat products (if you tolerate gluten)
- Sweet potatoes
- Green vegetables
3. Mixed Metabolism Foods
A mixed metabolism diet has a more-or-less even split of macronutrients. Aim for the following macronutrient ratio, broken down by calories:
- 30% fat
- 30% protein
- 40% carbs
Foods that fit into a mixed metabolism diet include:
- Red meat
- Fatty fish
- White fish
- Olive oil
- Sweet potatoes
- Fresh fruits
- Green vegetables
The metabolic type diet claims that people have different nutritional needs, depending on their metabolism. This is true — everyone’s body is unique, and it’s important to find a way of eating that makes you look and feel good.
However, the theory behind metabolic typing has no evidence to back it up, and the little research done on the metabolic type diet suggests that it doesn’t work — your metabolic type doesn’t seem to match up with your actual metabolism.
That said, the three diet plans that metabolic typing recommends are all based on proper nutrition, and are quite similar to other popular diets that do have a lot of research supporting them.
If you decide to try metabolic type dieting, pay attention to how you feel, and don’t be afraid to make changes if something isn’t working for you. Nutrition is individual, and the best diet is the one that gives you the results you want.