116: Can You Build Muscle on a Low-Carb Ketogenic Diet? What the Science Says with Dr. Ben Bikman

Bikman argues that on a low-carb diet, the reduced insulin could theoretically compromise the anti-catabolic defense, but abundant dietary amino acids fill this gap. Leucine is the key driver, as it directly turns on mTOR, leading to increased muscle protein synthesis. He cites studies where older adults gained lean mass with amino acid supplementation even without high insulin, and a study where women boosted IGF-1, a powerful anabolic hormone. The 2 g/kg target is in line with sports nutrition guidelines and ensures a robust supply of these anabolic signals. He emphasizes animal protein because it provides all essential amino acids in optimal ratios, unlike most plant proteins.

Bikman presents this as a way to capture ketone benefits without strict dieting. The 2018 human study infused BHB during LPS-induced inflammation and measured a 25% reduction in muscle protein breakdown compared to calorie-matched fats or placebo. The 2019 overtraining study in athletes found that BHB blunted the rise in stress hormones and allowed 15% better performance retention than glucose. He suggests these findings extend to any catabolic situation, like aging, bed rest, or weight cuts in sports. He advises choosing real BHB over precursors like MCT oil or ketone esters that might not deliver the same benefit, and mentions both salt and free acid forms are effective.

Bikman references his lab's work and a UC Davis paper showing that ketones significantly preserved muscle mass and strength in aging animals. The hind-limb unloading model demonstrated that BHB can prevent 80% of disuse atrophy, which mimics bed rest or reduced mobility common in aging. He argues that keeping ketone levels elevated, whether through diet or supplementation, is a prudent strategy to combat sarcopenia, one of the strongest predictors of longevity.

Dr. Bikman emphasizes that insulin's effect on muscle is to inhibit proteolysis, not to promote synthesis. He uses a construction site metaphor: insulin is like a security guard protecting the built structure, not a builder. Studies show that even at superphysiological levels, insulin alone does not elevate muscle protein synthesis. However, insulin can facilitate amino acid transport when amino acids are elevated, but it's a supporting role. This clarifies that the lower insulin levels on a ketogenic diet are not detrimental to muscle growth, as the anti-catabolic protection is still present, and amino acids drive the anabolic side.

Bikman argues that amino acids are the 'hero' and insulin a side player. Leucine, a branched-chain amino acid, is the primary activator of mTOR, the master growth regulator. He cites studies in older adults where leucine-rich supplements increased lean mass without high insulin, and another study in women where amino acids boosted IGF-1, an anabolic signal. He also notes that high levels of BCAAs can trigger a modest insulin release, which may help direct amino acids into muscle. Thus, the advice is to consume plenty of animal protein, around 2g/kg ideal body weight, to provide these amino acids. This fully supports muscle maintenance and gains in a low-insulin state.

Bikman explains that research shows the brain immediately takes up ketones as soon as they appear in the blood, even if glucose is more abundant. This challenges the idea that the brain 'prefers' glucose; in fact, glucose may be the backup. This neurological preference means less demand for glucose production by the liver. Gluconeogenesis often uses lactate and glycerol, but if the demand is extreme, amino acids from muscle are catabolized. By lowering the brain's glucose requirement, ketones preserve muscle protein. This is a key muscle-sparing mechanism of the ketogenic diet and explains why ketosis prevents muscle wasting during fasting versus starvation.

Dr. Bikman's lab published a study showing that muscle cells fueled with BHB had enhanced mitochondrial structure, higher ATP production, reduced oxidative stress, and resistance to toxic injury. In aging rodent models, BHB administration preserved more than 20% of muscle mass across fiber types, increased mitochondrial biogenesis, and reduced proteolysis; the mice also lived longer. In disuse atrophy models (hind-limb unloading), BHB prevented 80% of muscle loss by upregulating mTOR and reducing autophagy markers, while boosting glutamate for protein synthesis. This suggests ketones directly promote anabolic signaling and protect against catabolism, which has implications for sarcopenia, bed rest, and surgery.

Bikman details a 2018 human trial using LPS infusion to induce systemic inflammation, a catabolic state. Participants given BHB had significantly lower muscle protein breakdown (up to 25%) compared to controls receiving matched calories from free fatty acids or saline. In 2019, a study on athletes undergoing deliberate overtraining found that while glucose helped somewhat, the ketone group experienced lower stress markers and maintained 15% higher performance. This suggests that BHB, even without a ketogenic diet, can buffer against muscle loss during illness, bed rest, or intense training periods, and could be used for weight-cutting in combat sports.

Dr. Bikman references Jeff Volek's work, showing that fat-adapted athletes preserve glycogen by relying on fat oxidation and efficiently recycle glucose. Even if glycogen is depleted, it can be restored quickly via hepatic gluconeogenesis, which predominantly uses lactate and glycerol, not amino acids from muscle. This means keto-adapted individuals can sustain both endurance and possibly power output without carb loading.