The Fat Protein Efficient Diet: Explained

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If you’ve ever made your weight loss goals known to friends or family members, there’s a good chance that you received as many different diet recommendations as the number of people you spoke to, as almost everyone who has lost weight thinks they know the “best” diet to follow for successful weight loss.

Some people lose a ton of weight on popular low-carb diets like the Atkins diet, the South Beach Diet, or the ketogenic diet.

But on the other hand, some people seem to lose a lot of weight on low-fat diets by focusing on whole grains, vegetables, fruits, and other high-carbohydrate foods.

How is this possible, and what if you have found you don’t seem to lose weight with either approach?

The concept that some people metabolize certain types of foods better than others is embodied by a theory termed metabolic typing and is what we are going to explore today with yet another concept of dieting, a fat protein efficient diet.

We will discuss: 

  • What is a Fat Protein Efficient Diet?
  • How Do You Know If You Have a Fat Protein Efficient Metabolism?
  • What to Eat On a Fat Protein Efficient Diet

Let’s get started!

A person eating a plate of food on the protein fat efficient diet.

What is a Fat Protein Efficient Diet?

A fat-protein efficient diet, often written as the fat protein efficient diet, is one of the three primary metabolic types in the traditional metabolic typing scheme. It involves eating a diet high in protein and fat rather than high in carbohydrates.

The other two types of metabolisms in the metabolic typing scheme are carbohydrate-efficient metabolizers and mixed metabolizers.

But let’s take a step back. What is metabolic typing?

Metabolic typing is essentially the converse of a one-size-fits-all approach to weight loss. In other words, it takes into account individual variability in our metabolism and physiology based on our genes, hormones, and lifestyle.

While many people assume that they have a metabolism that is just “fast” or “slow,” proponents of metabolic typing believe this is an oversimplification that can greatly compromise your weight loss results. 

Instead, they believe that certain people oxidize or burn different fuel types better than others.

The theory of metabolic typing emerged during the 1970s, building upon some of the earlier findings of Weston A. Price, a Canadian dentist who reported that diet was only part of the entire picture of improving your health.

The theory of metabolic typing was based on the premise that metabolism can vary between two individuals based on their nervous system and their body’s oxidation rate of each of the three macronutrients.

According to the theory of metabolic typing, once you determine your metabolic type, you can achieve more efficient weight loss and feel healthier and more energized by eating foods that fall under the umbrella of your specific metabolic type.

In terms of dietary constituents, fat-protein efficiency refers to a diet that is high-protein and high-fat. 

A person seated at a kitchen island eating.

How Do You Know If You Have a Fat Protein Efficient Metabolism?

It’s important to note that there aren’t any official tests to determine your metabolic type. 

Metabolic typing diets have not been scientifically verified, so the fat protein efficient diet is merely based on a theory at this point. However, there are plenty of people who have found tons of success trying to determine their metabolic type and following the appropriate metabolic typing diet.

Based on the theory of metabolic typing, there are some characteristics of each of the three different metabolic types that can help you determine if you have a fat protein efficient metabolism.

If you have a fat protein efficient metabolism, you will tend to have a fast metabolism, and handle foods like meat, eggs, and nuts well. 

You may crave salty foods more than sweet foods and feel tired and grumpy after eating high-carbohydrate foods.

You may struggle to lose weight on a low-calorie diet, especially if you’re eating a lot of carbohydrates.

A variety of foods including meats, nuts, cheese, vegetables, oil, and avocado.

People who are said to be fat protein efficient tend to build muscle easily and have a strong appetite yet can be a healthy weight despite eating what seems like a lot of calories.

Fat protein efficient metabolic types are said to be “fast oxidizers” who are “parasympathetic nervous system dominant,“ whereas carbohydrate-efficient people are considered “slow” oxidizers and “sympathetic nervous system dominant.”

Carbohydrate-efficient metabolic types does well on lots of healthy whole grains but may feel heavy after rich meals high in protein and fat. They usually gravitate towards sweeter foods and “lighter” foods.

Based on their predominant nervous system, they tend to be high-strung or tenser than protein-fat oxidizers, who tend to be more even-keeled and relaxed.

Carbohydrate-efficient metabolic type people tend to struggle more with weight and gain weight easily.

Mixed metabolic types fall in the middle of the characteristics of fat protein efficient and carbohydrate-efficient metabolic types.

An avocado and almonds.

What to Eat On a Fat Protein Efficient Diet

Because there is an overall lack of scientific research about metabolic typing, there aren’t specific studies pointing to exactly what macronutrient ratio you should follow on a fat protein efficient diet.

However, it’s best to think of a fat protein efficient diet as a diet that is high in fat, high in protein, and low in carbohydrates. If you are familiar with other popular diets, you can think of the Atkins diet or keto diet as examples of fat-protein efficient diets.

A fat protein diet macronutrient breakdown is usually in the ballpark of 60% of the calories coming from fat, 30% from protein, and 10% from carbohydrates.

Athletes or those who want a more balanced ratio of fats to protein might do 40% protein, 40% fat, and 20% carbohydrates.

Still, others take a more balanced approach while still qualifying as a fat protein efficient diet, using a macronutrient ratio of 30% fat, 40% protein, and 30% carbohydrates. 

Almonds and cashews.

This latter approach can work well for endurance athletes who want to follow the fat protein efficient diet because you can time your carbohydrate intake around your workouts.

In this way, you can ensure you have the optimal fuel for high-intensity exercise while not going heavy-handed with carbohydrates at other points in the day when your body might be more sluggish when processing carbs.

As can be seen, carbohydrates don’t have to be pared back as severely as they are with keto, but the point is to focus on protein and fat since these are the macronutrients your particular body oxidizes best.

In most cases, playing around with what you eat and monitoring how you feel as a result can help you pinpoint the ideal macronutrient ratio when you’re following the fat-protein efficient diet (or any of the three metabolic typing diets).

Note that for reference, the carbohydrate-efficient diet usually gets 60% of the calories from carbohydrates, 15% from fat, and 25% from protein.

When you’re following the fat protein efficient diet, the quality of your fats and proteins matters as much as the relative quantities.

For any diet to be successful and beneficial for your overall health, you need to consume nutritious, natural foods with plenty of variety.

Let’s take a look at what works well on a fat protein efficient diet:

The word protein written on eggs.


Examples of good sources of protein on the fat protein efficient diet include organic beef, bison, veal, salmon, trout, eggs, scallops, muscles, liver and other organ meats, chicken, turkey, tuna, sardines, clams, and venison.

Avoid processed meats like sausages and bologna and lots of fatty cuts of meat like bacon, veal, and salami.


Examples of good sources of healthy fats on the fat protein efficient diet include avocados, coconut, olive oil, pecans, almonds, cashews, macadamia nuts, sunflower seeds, peanut butter, pumpkin seeds, squash seeds, flax seeds, full-fat organic, and eggs.

Avoid processed oils and trans fats, such as partially-hydrogenated palm oil or soybean oil in snack cakes and prepared muffins. Limit lard and vegetable shortening.

A variety of root vegetables.


For your carbohydrate intake, even though the relative percentage is small, quality still matters.

Focus on nutrient-dense carbohydrates from whole, natural food sources like vegetables, whole grains, beans, peas, lentils, tubers and root vegetables, and fruits.

If you don’t do well with starchy carbohydrates like pasta and potatoes, you can limit whole grains and starchy vegetables like sweet potatoes, carrots, yams, winter squash, corn, and parsnips.

With that said, you should still try to get plenty of leafy green vegetables, peppers, mushrooms, tomatoes, broccoli, cauliflower, Brussels sprouts, zucchini, asparagus, and low-sugar fruits like berries, melon, and citrus fruits. 

Legumes, such as beans, lentils, peas, and soy, can also be good sources of nutrient-dense carbohydrates for people with a fat-protein efficient metabolism.

Baskets of leafy greens.

Overall, some people do find success in losing weight by following the fat protein efficient diet after determining themselves to be a fat protein metabolizers. 

Remember, the entire concept of the metabolic type diet is just a theory, so conducting your own n=1 study with yourself as the subject is the best way to find what works for you.

Interested in looking into other popular diets? Check out our great diet guides for other diets that may work better for you:

Popular Diets For Runners: 3 Healthy Choices

The Golo Diet

The Zone Diet Guide

Intermittent Fasting

A basket of leafy greens.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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