How to Build Muscle on Keto: The Scientific Approach

Love it or hate it, keto is everywhere.

Is it good or bad? The truth is, keto is situational, and we’re not going to breed demagoguery in here.

The purpose of this article is to answer one question: is it possible to build muscle on keto? And if yes, how can we maximize the muscle growth?

Let’s break it down from the beginning.

Is It Possible to Build Muscle on Keto?

Let’s face it—keto is not optimized for building muscle. Actually, I wouldn’t be lying if I said that keto is optimized for NOT building muscle.

Evolutionally, keto is one of the mechanisms that help you stay alive in the absence of food. Keto is about burning tissues for energy, not building them. It’s cold outside, mammoths are hibernating, and the closest fruit tree is occupied by a hostile tribe… It’s time to convert body fat into ketones.

And I may be wrong about mammoths’ ability to hibernate, but no more. Does that mean building muscle on keto is impossible?


It’s much harder, and yet it’s possible. There are two basic prerequisites to building muscle. You must:

  1. Create stimuli strong enough to induce muscle growth.
  2. Have enough energy to create these stimuli.

These prerequisites can be created on any diet, the only question is how difficult this will be.

Let’s start with the stimuli.

How to Stimulate Muscle Growth

Why do muscles grow? Is it because you lift weights and damage muscle tissues or because of anabolic hormones?

At the most basic level, muscles improve because you repeatedly push them to the limit, challenging them to do something they struggle to cope with.

Trying to adapt to new challenges, muscles improve over time.

To improve doesn’t necessarily mean to grow. In fact, the two main directions in which your muscles can improve are their strength and endurance.

Both of these qualities are based on the same fundamental process—muscle contractions—but they are quite opposite in nature.

Strength (anaerobic) exercise is all about short-term muscle contractions with close-to-maximum contraction power.

Endurance (aerobic) exercise is all about long-term muscle contractions with significantly-below-maximum contraction power.

Most importantly, they utilize different muscle fibers: strength training mostly uses fast-twitch fibers; endurance training, mostly slow-twitch.

So, what about muscle hypertrophy?

Because muscle growth is a result of muscle adaptation to certain stimuli, the question is, which stimuli exactly?

Both science and the practice of bodybuilding agree that high-intensity short-term anaerobic training is best.

In simple words, if you want to grow muscles, you have to revolve your workout routine around training strength.

“Revolve” is there for a reason—strength training routines differ, and not all of them are ideal for muscle growth.

Let’s break it down.

Strength Training and Muscle Growth

  • In a nutshell, physical strength is the measure of force your muscles can create.

Your strength is limited by three factors:

  • Muscle properties (muscle cell size, fiber composition, etc.)
  • Recruitment intensity (how strong is the signal that tells muscles to contract)
  • Anthropometry (body proportions, force angles)

As you can see, the size of your muscles is just one of the factors that determine how strong you are. 

Or, in other words, you can increase strength without growing muscles. That’s why you shouldn’t follow a random strength training program.

(Especially on keto.)

Both scientific and empirical data suggest that anaerobic exercise with progressive overload in a range of 6–12 reps works best for muscle hypertrophy for the majority of people.

How many reps exactly should I do, 6 or 12? If keto wasn’t involved, I would answer that it doesn’t matter too much.

As for keto, the difference between 6 and 12 reps is massive.


Because of the second prerequisite—the energy.

What Fuels Muscle Contractions?

Your muscles don’t work directly on ketone bodies, glucose molecules, or fatty acids. These are just substrates that are used to produce ATP.

ATP, or adenosine triphosphate, is the principal source of energy that makes your muscles contract.

Your body can store only the small amount of ATP needed to fuel muscle contractions for roughly a couple of seconds. That’s because ATP molecules are larger and less stable than their substrates.

When you start burning ATP, your body launches several energy systems that replenish it. They overlap; however, certain systems dominate at certain periods of time.

The systems are:

  • Anaerobic creatine dephosphorylation. Creates ATP extremely fast, lasts for several seconds.   
  • Anaerobic glycolysis. Creates ATP fast, lasts for 1–2 minutes.
  • Aerobic glycolysis. Creates ATP at a medium pace, lasts for hours. Loses efficiency as glucose reserves become depleted.
  • Aerobic lipolysis. Creates ATP slowly, lasts for hours. Becomes more active as glucose reserves drop.

Anaerobic exercise, by definition, uses anaerobic metabolic pathways.

In anaerobic training, athletes who are not on keto are mainly limited by their glycogen stores and by lactate production. 

(Lactate production is a by-product of anaerobic pathways and causes muscle soreness.)

On keto, you’re limited by the lack of glucose and hence impaired anaerobic glycolysis. You’re pretty much left with stored ATP and anaerobic creatine dephosphorylation to fuel intense muscle contractions.

Have you noticed that anaerobic glycolysis lasts for minutes, and creatine dephosphorylation lasts for seconds? In simple words, with carbs you feel a gradual reduction in energy; without carbs, you become powerless at once after several seconds.   

Precisely after about 5–10 seconds, and this number primarily depends on your creatine reserves.


Creatine is an organic compound that facilitates ATP recycling. 

Your body produces creatine from the amino acids glycine and arginine. Then creatine gets phosphorylated and becomes phosphocreatine. Then, if you need an instant burst of energy, phosphocreatine donates its phosphate group to ADP to create ATP.

Knowing how creatine works is important; however, it’s more important to know that consuming more creatine can lead to an increase in phosphocreatine stores and hence to more energy available within a set.

Simply put, more creatine equals more reps.

Even though we synthesize creatine from protein-rich foods, supplementing creatine on keto is essential for every aspiring athlete. That’s because keto limits daily protein intake to 20–25% of daily calories and that is usually not enough to sustain large creatine reserves.

Summing Up, How to Build Muscle on Keto?

Traditional schemes advise using anaerobic routines with 6–12 reps, and keto limits your anaerobic capabilities to a maximum of 10 seconds of hard effort in a set.

When people try to fit their traditional 12-rep routine into a 10-second keto reality, they usually fail and start writing a revealing blog post about how it is impossible to build muscle on keto.

Whereas it is actually possible but takes a little bit of thinking.

This is what you should do to get keto gains:

  • Revolve your rep count around 5. Depending on your comfortable lifting pace, it might be 4, 5, or 6 reps.
  • Maximize your creatine reserves. Either supplement creatine or eat a lot of meat. Or better yet, both.
  • Keep your workout routine short. With a lack of fast energy, it is impossible for an anaerobic training session to last for long. But 30 minutes with the right approach can work wonders.
  • Focus on compound movements. You won’t have the energy to do enough isolation sets. Of course, you can break this rule if you are an advanced athlete (you know what you’re doing), or if you’ve had injuries.
  • Use split routines. Muscle hypertrophy and full-body programs are hard to combine, even without dietary restrictions. What do you expect from keto?

Rest enough between sets to recycle ATP and phosphocreatine and don’t go nuts performing a myriad of sets. Usually, 2–4 working sets is enough for an exercise.

The Closing Thought

Evolutionally, keto helped humans survive periods of starvation. When you starve, building new tissues is rather… questionable.

Luckily for us, evolution isn’t stupid.

Remember that hostile tribe from the beginning of the article? What if it attacks? Or what if we find a bison that doesn’t want to become a steak?

Are we doomed to die just because we can barely hold a spear, not to mention throwing it?  

Of course not. Evolution has given humans a creatine system, which can give a burst of energy even in the absence of carbs. Our ancestors used it to defeat an enemy or kill a mammoth, and we’re going to use it to push a barbell.

Building muscle on keto is hard, yet it’s possible with high-quality protein powder.

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