HMB

β-Hydroxy-β-methylbutyrate (HMB) is a naturally occurring compound made in the body from the amino acid leucine. While only a small percentage of leucine is converted into HMB, that small amount plays an outsized role in regulating muscle metabolism. It helps balance the scales between muscle growth and muscle breakdown—a balance that becomes harder to maintain with age, stress, injury, or intense training. When the body is under pressure, its ability to maintain lean mass falters. HMB supplementation helps tip the balance back, preserving strength and speeding recovery.

What is HMB

HMB is a metabolite of leucine, one of the key branched-chain amino acids that drive muscle protein synthesis. Unlike leucine, which works indirectly by triggering anabolic pathways, HMB operates both upstream and downstream: it stimulates new muscle building while actively suppressing the breakdown of existing muscle tissue.

It’s this dual action that makes HMB uniquely valuable. Instead of simply fueling new growth, it protects the structure you already have—giving you more resilience against loss when the body’s defenses weaken. HMB acts not just during training, but during recovery, injury, immobilization, and any period of high physical or metabolic stress.

Mechanisms of Action

HMB supports muscle health through two primary mechanisms. First, it promotes muscle protein synthesis by activating the mTORC1 pathway, encouraging muscle cells to grow, repair, and adapt. This pathway is central to recovery after exercise, injury, or metabolic stress.

Second, it inhibits muscle protein breakdown by reducing the activation of the ubiquitin-proteasome system, the body's major pathway for muscle degradation. By slowing down this internal demolition process, HMB preserves lean mass during catabolic states. Unlike leucine supplementation alone, HMB provides these effects without relying heavily on insulin spikes, making it useful in conditions where insulin sensitivity may be compromised—such as aging, illness, or prolonged inactivity.

What the Evidence Says

Clinical studies on HMB present a mixed but coherent picture. In populations facing muscle wasting—older adults, bedridden patients, or individuals recovering from serious illness—HMB consistently shows small but meaningful benefits in preserving lean mass and, in some cases, improving recovery outcomes.

Meta-analyses suggest that HMB supplementation can increase lean soft tissue mass modestly, especially when combined with other supportive measures like protein intake and resistance training. In athletic populations, results are more variable. Some studies report improvements in strength and body composition, while others show minimal effects, particularly in already well-trained individuals.

Overall, HMB is not a performance enhancer in the classic sense. It’s a preservation tool—designed to reinforce muscle structure under conditions where the body would otherwise tear itself down faster than it can rebuild.

Why We Use HMB

At FLCK, we don’t use ingredients because they’re trendy. We use them because they serve a specific, critical function.

HMB is not about instant strength gains or overnight transformation. It’s about holding the line. It helps slow the breakdown of muscle mass when the body is under siege—during intense physical exertion, during recovery, during aging, or during times when resilience matters more than hype.

We use HMB to support the system that hard work builds, not to replace it. Combined with proper training, nutrition, and recovery, it helps keep your base strong when the pressure is highest. That’s what real strength looks like: not just building, but defending what matters.