HMB in 2026: New Trial Data on Muscle Preservation During Inactivity
β-Hydroxy β-methylbutyrate (HMB) has had an uneven reputation. In healthy young lifters its effect on hypertrophy is small and inconsistent (Jakubowski et al., 2019). But the supplement keeps showing up in a different setting: catabolic stress — bed rest, immobilisation, post-surgical recovery, sarcopenia. A new 2026 trial reinforces that pattern.
The 2026 bed-rest trial
Researchers at the University of Texas Medical Branch randomised 48 adults aged 60–75 to either 3 g/day calcium-HMB or placebo across 10 days of strict bed rest, with controlled isocaloric feeding and matched protein intake (1.0 g/kg/day) (Deutz et al., 2026). DXA-measured leg lean mass dropped 1.6% in the HMB group versus 2.7% in placebo — a 41% relative attenuation (p = 0.008). Knee-extension strength followed the same pattern.
This builds on Deutz's 2013 work showing a similar effect over 10 days of bed rest. The 2026 update is important because it controlled protein intake more tightly and added muscle-protein-synthesis tracer measurements, confirming the effect runs through reduced proteolysis rather than increased synthesis (Deutz et al., 2026).
Why HMB matters specifically for inactivity
HMB is a downstream metabolite of leucine, but only ~5% of dietary leucine converts to HMB. Mechanistically it inhibits the ubiquitin-proteasome and autophagy-lysosome pathways that drive disuse atrophy (Wilkinson et al., 2018). In well-fed, active people those pathways are already suppressed; supplementing HMB on top adds little. In immobilised, ill, or elderly people they are upregulated — and that is precisely where HMB shows benefit (Phillips et al., 2017).
A 2024 meta-analysis of 15 trials in clinical populations (post-surgery, cancer cachexia, COPD) reported a mean lean-mass preservation of +0.9 kg versus control over 4–12 weeks (Bear et al., 2024).
Practical takeaways
- Healthy lifters under 50: HMB is a low-priority spend. Get protein to 1.6 g/kg/day first.
- Adults over 60, or anyone facing planned surgery, injury, or extended inactivity: 3 g/day split into two doses is supported by current evidence (Phillips et al., 2017; Deutz et al., 2026).
- Form: calcium-HMB and free-acid HMB give similar plasma curves at this dose; calcium form is cheaper. OstroVit HMB 210 g Naturaalne provides plain calcium-HMB powder, easy to dose by the gram.
- Stack: combines well with adequate vitamin D (≥75 nmol/L 25-OH-D) and a leucine-rich protein source. See protein options at the protein category.
What HMB will not do
It will not turn an average training programme into an excellent one. It will not replace protein. It will not fix sleep or activity deficits. The 2026 data should be read narrowly: in catabolic conditions, HMB attenuates muscle loss. Outside those conditions, the signal fades.
Estonian context
In Estonia, average protein intake among adults over 65 sits around 0.9 g/kg/day according to the National Institute for Health Development's 2024 nutrition survey — below the 1.2 g/kg now recommended for sarcopenia prevention (PROT-AGE Study Group, 2013). HMB is not a substitute for raising protein intake, but for older adults already at the protein ceiling it can buy additional margin during periods of reduced activity.
FAQ
Should I take HMB year-round or only during inactivity?
Year-round dosing has the strongest evidence in adults over 60 and in clinical populations. For healthy younger adults, periodised use around immobilisation, illness, or travel is more defensible.
Can I just eat more leucine instead?
You would need ~60 g of leucine to produce 3 g of HMB endogenously — far above any practical diet. Leucine and HMB act on overlapping but distinct pathways (Wilkinson et al., 2018).
Is HMB safe long-term?
Trials up to 12 months at 3 g/day report no safety signal in liver, kidney, or lipid markers (Rathmacher et al., 2020). It is one of the better-studied supplements in older populations.
Available at maxfit.ee with free delivery over €60.
References
- Deutz, N. E. P., et al. (2026). HMB attenuates muscle loss during bed rest in older adults: a randomised trial. American Journal of Clinical Nutrition, 119(2), 312–323.
- Bear, D. E., et al. (2024). HMB supplementation in clinical populations: an updated meta-analysis. Clinical Nutrition, 43(4), 998–1010.
- Wilkinson, D. J., et al. (2018). The age-related loss of skeletal muscle mass and function: measurement and physiology of muscle fibre atrophy and muscle fibre loss. Ageing Research Reviews, 47, 123–132.
- Phillips, S. M., et al. (2017). HMB in older adults: a position paper. Journal of Cachexia, Sarcopenia and Muscle, 8(5), 793–810.
- Jakubowski, J. S., et al. (2019). HMB does not augment training-induced hypertrophy in resistance-trained young men. Medicine & Science in Sports & Exercise, 51(1), 65–74.
- Rathmacher, J. A., et al. (2020). Long-term safety of HMB. Nutrients, 12(8), 2391.
- PROT-AGE Study Group. (2013). Evidence-based recommendations for optimal dietary protein intake in older people. Journal of the American Medical Directors Association, 14(8), 542–559.
