β-Hydroxy β-Methyl Butyrate, or HMB for short, holds particular esteem within weightlifting and fitness training circles. It’s a metabolite produced through the breakdown of Leucine, an essential amino acid. It helps to prevent muscle fatigue while increasing overall strength and muscle size.
Essentially, Leucine helps to slow down protein breakdown and speed up overall protein synthesis. It is particularly significant for individuals dealing with muscle soreness or endurance issues. However, our bodies cannot produce Leucine on its own. It is naturally found in food sources such as soybeans, seeds, meat, fish, lentils and milk. That said, there is a small caveat, namely: Absorption rate.
Only 5% of dietary Leucine is broken down into HMB. Therefore a natural diet cannot provide a significant dosage of the compound to optimise muscle protein synthesis. Supplementation of HMB has shown statistically substantive benefits on gains. While there is debate around its effectiveness for lightly to heavily trained lifters, research has produced some impressive results.
Reported Effects of HMB
1. Increases Protein Absorption
According to research, HMB improves protein synthesis in skeletal muscles by stimulating mTOR (a protein kinase which regulates cell growth) (1). The 12-week study concluded that the compound provides an anabolic effect while also being anti-catabolic—even while following a calorie-restricted diet.
Athletes did experience an improvement in their results. Still, new lifters and elderly individual report significant changes resulting from HMB supplementation. To study its impact on absorption rates, undertaking additional research is crucial; however, the muscle growth experienced by participants is overall encouraging.
2. Improves Strength And Endurance
Aside from muscle size, studies also illustrate a positive impact on performance. In one controlled study, supplementing overweight women with HMB for six weeks led to improvements in their strength. Results are significantly impressive given without any weight training (2).
Another research looked at the endurance of trained cyclists. The 32-week supplementation showed positive effects on their performance according to their VO2 peak and lactic acid build-up (3).
3. Faster Recovery
Numerous studies suggest improvements in physique or performance can be attributed to HMB’s impact on recovery.
In one study, supplementing 3g of the compound led to a decreased amount of muscle proteolysis. Participants weight lifted for 1.5 hours for 3 days a week for 3 weeks. Additionally, a 7-week follow-up research extended the parameters to 2-3 hours for 6 days, with similar results. Both studies displayed participants experienced less muscle soreness or damage and had more massive gains from resistance training (4).
Common Supplements that Contain HMB
Due to its measured effects, refined HMB is often marketed on its own as a tablet or powder. It is typically derived from Calcium. Therefore it may be labelled as Cal-HMB.
Recently, the compound has also been made available in its free acid form—referred to as FA-HMB. In this form, HMB reportedly:
- Has better absorption rates – It transports compounds higher into your body
- Works quicker – Cal-HMB typically takes 120 minutes to reach its peak; whereas, in its free acid form, it takes only 30 minutes.
That said, limited safety and dosage research on FA-HMB should be taken into account. Due to being relatively new to the market, the guidelines are meagre and the cost is relatively high.
The compound is also an ingredient in various performance or recovery blends. Moreover, Leucine is present in most BCAAs and could provide less-potent, but similar effects. Other combinations may include blends with Creatine, L-Carnitine and HICA.
Creatine, in particular, acts a powerful accessory to HMB. According to one study, supplementing the duo led to an increase in muscle and strength in 40 participants. The study has placebo participants and also took individual supplementation of each component; the results of the combination outweighed the others (5)
Side Effect of HMB Supplementation
HMB is backed by numerous research trials, and is deemed safe.
Participants of these studies include a spectrum of fitness levels, ages and genders (6). Additionally, clinical trials have extended from up to a year without any safety concerns (7). More research into HMB and its side effects need to be explored. At present, only one study suggests the compound may lower glutamine which may have an impact on immunity (8). Users have reported nausea, stomach pain or diarrhea from its liquid form.
HMB dose is a vital component of supplementation. Lowered dosage is generally less effective. According to the recommended standards, 3 grams of HMB produces expected results.
In regards to supplementation, it is approximately 3 capsules a day; given most brands package it as 1000mg per capsule. Therefore, 3 servings a day should provide your body with the boost it needs.
Additionally, recommended dosage guidelines are dependent on limited research, as such dosage for FA-HMB needs evaluation.
- Wilson, J.M., Fitschen, P.J., Campbell, B. et al. International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB). J Int Soc Sports Nutr 10, 6 (2013). https://doi.org/10.1186/1550-2783-10-6
- Hashempour, A., Hooshmand, S., Tabesh, M. R., & Alizade, Z. (2019). Effect of 6-week HMB (beta-hydroxy-beta methylbutyrate) Supplementation on Muscle Strength and Body Composition in Sedentary Overweight Women. Obesity Medicine, 100115.
- Vukovich MD, Dreifort GD. Effect of beta-hydroxy beta-methylbutyrate on the onset of blood lactate accumulation and V(O)(2) peak in endurance-trained cyclists. J Strength Cond Res. 2001;15(4):491-497.
- Nissen S, Sharp R, Ray M, et al. Effect of leucine metabolite beta-hydroxy-beta-methylbutyrate on muscle metabolism during resistance-exercise training. J Appl Physiol (1985). 1996;81(5):2095-2104. doi:10.1152/jappl.19184.108.40.2065
- Jówko E, Ostaszewski P, Jank M, et al. Creatine and beta-hydroxy-beta-methylbutyrate (HMB) additively increase lean body mass and muscle strength during a weight-training program. Nutrition. 2001;17(7-8):558-566. doi:10.1016/s0899-9007(01)00540-8
- Sanchez-Martinez J, Santos-Lozano A, Garcia-Hermoso A, Sadarangani KP, Cristi-Montero C. Effects of beta-hydroxy-beta-methylbutyrate supplementation on strength and body composition in trained and competitive athletes: A meta-analysis of randomised controlled trials. J Sci Med Sport. 2018;21(7):727-735. doi:10.1016/j.jsams.2017.11.003
- Baier S, Johannsen D, Abumrad N, Rathmacher JA, Nissen S, Flakoll P. Year-long changes in protein metabolism in elderly men and women supplemented with a nutrition cocktail of beta-hydroxy-beta-methylbutyrate (HMB), L-arginine, and L-lysine. JPEN J Parenter Enteral Nutr. 2009;33(1):71-82. doi:10.1177/0148607108322403
- Holecek M, Muthny T, Kovarik M, Sispera L. Effect of beta-hydroxy-beta-methylbutyrate (HMB) on protein metabolism in whole body and in selected tissues. Food Chem Toxicol. 2009;47(1):255-259. doi:10.1016/j.fct.2008.11.021