Here’s why taking a supplement like Clear Muscle is the most convenient and cost-effective way of getting this powerful ingredient!
It’s generally accepted that approximately 5% of dietary leucine is converted to HMB (β-hydroxy β-methylbutyrate) in the human body. This figure comes from metabolic studies examining how leucine, an essential branched-chain amino acid, is processed after ingestion. Here’s the breakdown of why this is the case and what the science says:
Table of contents
Metabolic Pathway
Leucine is metabolized primarily in the liver and skeletal muscle. After ingestion, it undergoes one of two main fates:
- Protein Synthesis : Most leucine is used to build proteins or support muscle repair and growth.
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Oxidation: A smaller portion is oxidized via the enzyme branched-chain amino acid aminotransferase (BCAT), producing α-ketoisocaproate (KIC). KIC can then follow two paths:
- Further Oxidation : Most KIC is converted to isovaleryl-CoA and enters energy production pathways.
- HMB Production : A minor fraction of KIC is converted to HMB by the enzyme α-ketoisocaproate dioxygenase, primarily in the liver cytosol.
Only about 5% of ingested leucine takes this HMB pathway, while the rest is either incorporated into proteins or oxidized for energy.
Evidence Supporting the 5% Conversion Rate
- Early Studies : Research from the 1990s, including work by Nissen and colleagues (who pioneered HMB supplementation), estimated that ~5% of leucine is metabolized into HMB. This was based on tracer studies and measurements of HMB production in animals and humans after leucine administration.
- Metabolic Balance : In a 70 kg person, daily leucine intake from a typical diet (e.g., 5–10 g) yields ~0.25–0.5 g of HMB naturally. For example, 10 g of leucine × 0.05 = 0.5 g HMB, aligning with observed endogenous levels (~0.3–0.6 g/day).
- Pharmacokinetic Data : When supplemental leucine is given (e.g., 20–50 g), urinary HMB excretion increases modestly (e.g., ~1–2 g), suggesting a consistent 5% conversion. Studies also show that to achieve 3 g of HMB, ~60 g of leucine is needed (60 g × 0.05 = 3 g), reinforcing this rate.
Factors Influencing Conversion
The 5% figure is an average and can vary slightly:
- Individual Metabolism : Enzyme activity (e.g., α-ketoisocaproate dioxygenase) differs between people, potentially altering HMB yield.
- Dietary Context : High protein intake or fasting might shift leucine toward oxidation, slightly changing HMB production.
- Species Differences : Pigs and sheep convert closer to 10–15% of leucine to HMB, but human data consistently hover around 5%.
Why Not More?
HMB production is a minor pathway because:
- The enzyme converting KIC to HMB has limited capacity and is not highly expressed.
- Most leucine is prioritized for protein synthesis or energy, especially during exercise or fasting.
- HMB is rapidly cleared (e.g., ~20% excreted in urine), reducing net accumulation.
Conclusion
The 5% conversion rate is true based on current scientific understanding. It’s a well-established estimate from metabolic research, though it’s not an exact, universal constant—more of a practical average. This low efficiency is why Clear Muscle is such a game changer: you’d need to consume ~60 g of leucine (e.g., ~8 kg of chicken breast) every day to match that dose through diet alone!
From whey protein, you would need 24 servings of whey protein concentrate (with 24g protein per serving) to get at least 60g of leucine. That’s 26 scoops of protein to get 3g of HMB daily!
The choice is clear! With just 3 easy-to-take soft gels each day, Clear Muscle is the only option for anyone looking to take advantage of the powerful anabolic/anti-catabolic effects of HMB.
