Creatine or HMB: What's the Difference

Creatine and HMB are often marketed as "supplements for muscle growth," but they work in completely different ways. The editorial team examined where each substance comes from, which process in the muscle it affects, how convincing the research is, and which myths surrounding them have no basis.

Two different molecules with different histories

Creatine and HMB (beta-hydroxy-beta-methylbutyrate) often sit on the same shelf of a sports shop, and buyers perceive them as interchangeable "muscle supplements." In reality these are substances with different origins, different biochemistry and very different levels of evidence. The editorial team explains how they actually differ, rather than by marketing promises.

Creatine is a nitrogen-containing organic acid that the body synthesizes from three amino acids: arginine, glycine and methionine. A person covers about half of the daily requirement through their own synthesis in the liver and kidneys, and obtains the rest from meat and fish. Over 90% of creatine stores are concentrated in skeletal muscle.

HMB is a metabolite of the essential amino acid leucine. Only a small fraction of leucine, by various estimates around 5%, is converted into HMB in the body. That is why it is practically impossible to obtain meaningful amounts of HMB from food: doing so would require very large quantities of protein products.

Historically, creatine became a mass-market supplement after the 1992 Olympic Games, while HMB drew attention following research by Steven Nissen's group in the mid-1990s. Since then creatine has been the subject of hundreds of controlled studies, whereas the body of data on HMB is considerably smaller and more contradictory.

Mechanism of action: energy versus protein protection

The main difference lies in the point of action. Creatine works as an energy buffer. In the muscle it exists mainly as creatine phosphate, which, with the help of creatine kinase, rapidly regenerates ATP during short intense efforts. Taking the supplement raises intramuscular stores of creatine and creatine phosphate.

A larger store of creatine phosphate means an athlete can perform slightly more repetitions in a set or recover faster between sprints. It is precisely this increase in the volume of quality work that, over time, translates into gains in strength and muscle mass. In addition, creatine increases the water content in muscle cells, which is also considered one of the signals for growth.

HMB acts differently: it is regarded as an anticatabolic agent. It is thought to reduce the breakdown of muscle protein (in particular through the ubiquitin-proteasome pathway), to slightly stimulate protein synthesis via mTOR, and to take part in stabilizing cell membranes as a precursor of cholesterol in muscle cells.

So creatine helps you train more intensely, while HMB theoretically helps you lose less muscle tissue under stress. This difference explains why the effect of creatine is noticeable in almost any trained athlete, whereas the effect of HMB is best seen where catabolism is pronounced: in beginners, older people, and during immobilization.

• Creatine:ATP resynthesis, increased training volume, cell hydration.
• HMB:reduced proteolysis, moderate stimulation of protein synthesis, possible membrane stabilization.

What the research says

Creatine monohydrate is one of the few supplements that the 2018 International Olympic Committee consensus classes among agents with good evidence of effectiveness. Meta-analyses record gains in strength and lean mass when combined with strength training, in men and women alike, in the young and the old.

For HMB the picture is less clear-cut. Nissen's early work showed a reduction in markers of muscle damage and a gain in strength in untrained people. However, the 2009 meta-analysis by Rowlands and Thomson concluded that in trained athletes the effect on strength and body composition is small or trivial.

The ISSN position on HMB (2013) is more optimistic; however, some of the positive studies, especially those with free-acid HMB, were later criticized because of unusually large effects that independent groups were unable to reproduce. The editorial team considers it appropriate to treat these results with caution.

Practical takeaway: creatine has a stable, reproducible effect; HMB's is small and context-dependent. This does not make HMB useless, but it moves it from the category of "foundational" to the category of "situational" supplements.

Comparison table

To summarize the differences, we brought the key parameters together in a table. It does not replace an individual consultation, but it lets you quickly get your bearings on exactly how these two substances differ.

Note the difference in cost: creatine monohydrate is one of the cheapest supplements per daily dose, whereas an effective dose of HMB usually costs several times more. Given the weaker evidence base, this is a substantial argument.

One more nuance is the forms. For creatine the "gold standard" remains monohydrate; more expensive forms (hydrochloride, buffered creatine) have not proven any advantage in comparative studies. HMB is produced as a calcium salt (HMB-Ca) and as a free acid (HMB-FA), and the latter form is absorbed faster, although an advantage for results has not been proven.

Finally, neither substance is a doping agent and neither is on the WADA Prohibited List. However, for athletes who undergo testing it is important to choose products with independent certification, since the risk of contamination applies to any supplement.

Safety and common myths

Creatine is one of the best-studied supplements from a safety standpoint. In healthy people at recommended doses no harm to the kidneys or liver has been found. At the same time, creatine raises blood creatinine levels, which may be mistakenly interpreted as a decline in kidney function, so you should tell your doctor about taking it before tests.

The widespread myth that creatine "dehydrates" and causes cramps is not supported by research. Likewise there is no evidence that it causes baldness: the well-known study showing a rise in dihydrotestosterone in rugby players did not measure hair loss and has still not been reproduced.

HMB also has a favorable safety profile: in studies with doses up to 6 g per day no serious side effects were recorded. Mild stomach discomfort is occasionally mentioned. People with kidney or liver disease, as with creatine, need a doctor's consultation.

Another myth is that HMB and creatine "conflict" with each other. There are no data on a negative interaction; several studies examined their combination, but an additional benefit from HMB on top of creatine in trained people has not been convincingly shown.

Editorial conclusions

Creatine and HMB are not analogues but substances with different jobs. Creatine boosts the energy supply for short intense efforts and has one of the strongest evidence bases among sports supplements.

HMB is aimed at reducing the breakdown of muscle protein. Its effect in trained athletes is small, and it is most interesting for situations of pronounced catabolism - for example, in old age or during a forced break from training.

If your budget is limited and your goal is strength and muscle mass, it is sensible to start with creatine monohydrate. HMB should be considered as an additional, situational tool, not a replacement.

For a deeper understanding of the topic we recommend our materials on the forms of creatine and how they differ, on leucine and muscle protein synthesis, and on the safety of creatine for the kidneys.

References

1. Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017;14:18.
2. Wilson JM, Fitschen PJ, Campbell B, et al. International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB). J Int Soc Sports Nutr. 2013;10(1):6.
3. Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med. 2018;52(7):439–455.
4. Rowlands DS, Thomson JS. Effects of beta-hydroxy-beta-methylbutyrate supplementation during resistance training on strength, body composition, and muscle damage in trained and untrained young men: a meta-analysis. J Strength Cond Res. 2009;23(3):836–846.
5. Nissen S, Sharp R, Ray M, et al. Effect of leucine metabolite β-hydroxy-β-methylbutyrate on muscle metabolism during resistance-exercise training. J Appl Physiol. 1996;81(5):2095–2104.
6. Lanhers C, Pereira B, Naughton G, et al. Creatine supplementation and lower limb strength performance: a systematic review and meta-analyses. Sports Med. 2015;45(9):1285–1294.