Can You Build Muscle on a Ketogenic Diet?


Well-known member
May 24, 2021
Can You Build Muscle on a Ketogenic Diet?

Many detractors of the ketogenic diet will often cite the “fact” that you cannot build muscle on the diet and in fact without a significant intake of carbohydrates and protein you will actually lose muscle. The common belief is that in order to build muscle you must eat A LOT of protein as well. In my experience and the anecdotal reports (including bodybuilders) this is not true. A common practice with bodybuilders is to “bulk up” with a surplus of macro nutrients (especially protein) to place the body in anabolic state. After this phase, comes the “cut” phase, where often carbohydrates are drastically reduced in an effort to lose body fat. But, what does the science say about building muscle while on a ketogenic diet? I wanted to see what studies have been done to examine this issue. Here is what I found…

To start, we need to know what conditions are needed in the body to “build muscle”. One process that must exist is a positive protein balance. The body is continually in a process of building and breaking down (i.e., anabolism and catabolism respectively). It’s often thought that you are building muscle when you lift weights, but in reality, this is a time when muscle tissues are being broken down and protein is being lost. This process is also known as Muscle Protein Breakdown (MPB). Under the appropriate conditions, after muscle has been broken down (via resistance exercise), it will rebuild and repair itself while adding additional muscle tissue.

When the correct conditions for muscle repair exist, another process will occur called Muscle Protein Synthesis (MPS). This is the process that occurs when the amino acids (building blocks of protein) necessary for repair and growth are being produced. Naturally, MPS must exceed MPB in order to grow new muscle tissue. Among the most important amino acids needed to build muscle are the Branched Chain Amino Acids (BCAAs). BCAAs consist of leucine, isoleucine and valine. Leucine is considered the most critical amino acid to promote MPS.

A study entitled “Effect of, b-Hydroxybutyrate on Whole-Body Leucine Kinetics and Fractional Mixed Skeletal Muscle Protein Synthesis in Humans” published in 1988 at the University of Rochester examined what effect beta-hydroxybutyrate has on leucine oxidation and MPS in humans. It had been previously observed that there is a conservation of protein that occurs when fasting and it was hypothesized that a state of ketosis could be related to this phenomenon. The researchers set out to examine if this hypothesis was correct or not. The participants in the study were admitted to the University of Rochester Clinical Research Center with subjects receiving identical preparations before the experiment with each subject placed on a “weight-maintaining diet (composition as percentage of calories from carbohydrate/fat/protein = 45:40:15).”

Two separate studies were conducted: “one study was performed to measure the effect of b-OHB infusion on leucine metabolism, and the other was performed with normal saline infusion (control experiment).” Each of the participants also received an infusion of leucine. After examining all the data collected the authors concluded: “In summary, we conclude that a small physiological increase in, b-OHB concentrations decreases leucine oxidation and enhances incorporation of leucine into muscle protein in humans.”

Another common argument as to why you must consume carbohydrates in addition to protein is that the carbohydrates will spike insulin thereby stimulating MPS and driving protein into muscle cells. On the surface this would seem to make sense when considering insulin is an anabolic hormone. A study entitled “Carbohydrate does not augment exercise-induced protein accretion versus protein alone” published in 2011 at the Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada put this theory to the test.

The researchers from the Exercise Metabolism Research Group stated their purpose was to test “the thesis that CHO and protein coingestion would augment muscle protein synthesis (MPS) and inhibit muscle protein breakdown (MPB) at rest and after resistance exercise.” Their methods of study were: “Nine men (age=23.0±1.9 yr, body mass index=24.2±2.1 kg·m) performed two unilateral knee extension trials (four sets×8-12 repetitions to failure) followed by consumption of 25 g of whey protein (PRO) or 25 g of whey protein plus 50 g of maltodextrin (PRO+CARB). Muscle biopsies and stable isotope methodology were used to measure MPS and MPB.”

As you might have guessed from the title of the study, there was no resulting benefit in MPS when consuming carbohydrates with protein. Analysis of the data led the authors to concluded: “Our data suggest that insulin is not additive or synergistic to rates of MPS or MPB when CHO is coingested with a dose of protein that maximally stimulates rates of MPS.” This study confirmed a similar study entitled “Coingestion of carbohydrate with protein does not further augment postexercise muscle protein synthesis” completed in the Netherlands in 2007 which concluded: “coingestion of carbohydrate during recovery does not further stimulate postexercise muscle protein synthesis when ample protein is ingested.”

What will probably come to a great surprise to many people is the effect the ketogenic diet has on glycogen stores in the body. A study entitled “Metabolic characteristics of keto-adapted ultra-endurance runners” published in 2015 that was performed by two of the early pioneers (as well as others) in the science of keto. Dr. Jeff Volek & Dr. Stephen Phinney, examined the “metabolic adaptions” that occur in “keto adapted” athletes.

One of the potential problems that ketogenic studies have is that participants are not usually what would be considered “keto adapted”. Often individuals in these studies are in a state of ketosis, but have not been in this state for more than 2-3 weeks. There is evidence that it takes time to optimally adapt to burning primarily ketones for energy. In that light, the researchers included a cohort of “elite ultra-marathoners and ironman distance triathletes” that had been in ketosis for an average of twenty months. The other group of athletes consumed a traditional high carb diet.

The data revealed that the keto adapted athletes burned fat at an incredibly high rate (“mean fat oxidation during submaximal exercise was 59% higher in the LC group”) AND their glycogen stores were found to be virtually the same as the high carb athletes (“there were no significant differences in resting muscle glycogen and the level of depletion after 180 min of running”).

In the authors discussion of the study, they summarized their findings thus:

In summary, these results provide the first documentation of the metabolic adaptations associated with long-term consumption of a very low-carbohydrate/high-fat diet in highly trained keto-adapted ultra-endurance athletes. The enhanced ability to oxidize fat during exercise across a range of intensities is striking, as is the ability to maintain “normal” glycogen concentrations in the context of limited carbohydrate intake. Keto-adaptation provides an alternative to the supremacy of the high-carbohydrate paradigm for endurance athletes.

So, these studies seem to indicate that there are essentially two things you need to build muscle: resistance training and adequate protein (primarily Branched Chain Amino Acids) with a positive protein balance. In addition, like most other processes in the body, carbohydrates are not essential to the building of muscle. At the very least, it appears that being in a state of ketosis does not impair muscle protein synthesis. For those that want to maximize their strength:weight, the ketogenic would seem to be ideal, but that is another topic to explore at another time!