GradedHealth

Does HMB help you keep muscle as you age?

Early trials suggest HMB, a leucine byproduct, may help older adults keep a little muscle. The gains are small, and exercise seems to matter more.

Published October 2026

Short answer

Early, modest evidence: HMB may help older adults keep some muscle, but the gains are small and it adds little to resistance training. Evidence grade C (Limited). Several meta-analyses of mostly small trials; downgraded for inconsistency, risk of bias and reliance on muscle mass as a surrogate.

Key takeaways

  • Meta-analyses of trials in older adults show a small gain in muscle mass with HMB [1][2].
  • Strength and walking results are inconsistent, and HMB added to resistance training did not improve muscle mass or strength in a 2026 meta-analysis [3].
  • Most trials are small or at risk of bias, so the effects are modest and uncertain [4][5].
  • In a 12-month trial, HMB with vitamin D helped people who did not exercise but added nothing for those who did [6].

The short version

HMB (beta-hydroxy-beta-methylbutyrate) is a metabolite of the amino acid leucine, sold as a supplement for keeping muscle [1]. In older adults, early trials suggest it may help preserve a little muscle mass, but the gains are small and the results are mixed [2][3]. When HMB is added to resistance training, the extra benefit disappeared in the newest meta-analysis [3].

What the studies show

Several meta-analyses of randomised trials in older adults found a small gain in muscle mass. Seven trials with 287 older adults found more muscle mass gain on HMB than on control [1]. Nine trials with 448 people found a rise in fat-free mass, with no change in fat mass [7]. An umbrella review of meta-analyses from 2025 found a small gain in muscle mass and strength, with no change in fat mass or body weight [2].

Strength and walking results are less consistent. Across a range of clinical conditions, HMB gave a small strength gain in one 2019 review [5]. A 2026 meta-analysis of 13 trials in adults aged 50 and over found that HMB added to resistance training did not improve muscle mass or strength [3]. A 2025 meta-analysis found a moderate improvement in a physical performance test when HMB was combined with resistance training [4]. An earlier umbrella review found no evidence that HMB improved physical function [8].

For muscle loss from bed rest, one small trial of 24 healthy older adults on 10 days of bed rest found that HMB prevented the drop in lean body mass seen in the placebo group [9]. Only 19 people were analysed, so a larger study is needed to confirm it. In critically ill adults, HMB did not improve walking or physical performance in two trials [10][11].

The nuances

Most trials are small and short, and many gave HMB with other nutrients. In the 2022 cancer review, most studies combined HMB with amino acids or gave it in shakes, so HMB's own effect is hard to separate [12]. Quality is also a concern: half of the trials in the 2025 meta-analysis were at high risk of bias [4], and none of the trials in the 2019 review were at low risk of bias in every category [5].

Exercise seems to matter more than the supplement. In men and women aged 65 and over, 24 weeks of resistance training improved strength and lean mass, with no extra gain from HMB in the exercise groups [13]. In a 12-month trial, HMB with vitamin D added lean mass in people who did not exercise, but not in people who did [6]. In older adults with sarcopenia, HMB with resistance training gave greater handgrip gains than placebo with training, though muscle mass did not differ [14]. Pre-frail adults who drank a high-protein shake with 3 g of HMB a day for 12 weeks gained more thigh muscle area than controls [15].

Not every trial was positive. In a 6-month trial in people on haemodialysis, HMB did not change muscle, strength or physical function [16]. A 12-week pilot in cirrhosis found no difference in muscle mass compared with control [17].

Side effects were rare in the trials. The 2022 cancer review reported no serious adverse effects from the nutrition intervention [12]. In one ICU trial, high blood sugar occurred in 3 of 134 patients given HMB [11]. The trials did not report on pregnancy, interactions with medicines or long-term use, so see the HMB topic page for what is and is not known.

Several authors of the 2022 cancer review report ties to Abbott Nutrition [12]. The company sells HMB-containing shakes such as Ensure Plus Advance, which one trial used [15].

What this means for you

In these trials, resistance training was the clearest driver of strength and lean-mass gains [13]. HMB may add a small benefit on its own, but it is not a replacement for exercise, and it did not add to exercise in the newest review [3]. Talk with a doctor or dietitian before starting HMB, especially if you have kidney or liver disease, diabetes, or take other medicines.

Go deeper

  • HMB — HMB, a leucine byproduct, gives older adults a small gain in muscle mass and strength in some trials.

References

  1. Effect of beta-hydroxy-beta-methylbutyrate supplementation on muscle loss in older adults: a systematic review and meta-analysis.. Arch Gerontol Geriatr, 2015.
  2. Ergogenic Benefits of β-Hydroxy-β-Methyl Butyrate (HMB) Supplementation on Body Composition and Muscle Strength: An Umbrella Review of Meta-Analyses.. J Cachexia Sarcopenia Muscle, 2025.
  3. Efficacy of HMB supplementation as an adjunct to resistance training in older adults: a comprehensive meta-analysis.. Age Ageing, 2026.
  4. The Role of HMB Supplementation in Enhancing the Effects of Resistance Training in Older Adults: A Systematic Review and Meta-Analysis on Muscle Quality, Body Composition, and Physical Function.. Nutrients, 2025.
  5. β-Hydroxy-β-methylbutyrate and its impact on skeletal muscle mass and physical function in clinical practice: a systematic review and meta-analysis.. Am J Clin Nutr, 2019.
  6. Long-term Effects of Calcium β-Hydroxy-β-Methylbutyrate and Vitamin D3 Supplementation on Muscular Function in Older Adults With and Without Resistance Training: A Randomized, Double-blind, Controlled Study.. J Gerontol A Biol Sci Med Sci, 2020.
  7. Effects of oral administration of β-hydroxy β-methylbutyrate on lean body mass in older adults: a systematic review and meta-analysis.. Eur Geriatr Med, 2021.
  8. An umbrella review of systematic reviews of β-hydroxy-β-methyl butyrate supplementation in ageing and clinical practice.. J Cachexia Sarcopenia Muscle, 2022.
  9. Effect of β-hydroxy-β-methylbutyrate (HMB) on lean body mass during 10 days of bed rest in older adults.. Clin Nutr, 2013.
  10. Effects of a multilevel intervention of resistance training with or without beta-hydroxy-beta-methylbutyrate in medical ICU patients during entire hospitalisation: a four-arm multicentre randomised controlled trial.. Crit Care, 2023.
  11. Resistance training and β-hydroxy-β-methylbutyrate for functional recovery in critical illness: a multicenter 2 × 2 factorial randomized trial.. Crit Care, 2025.
  12. Effects of β-hydroxy β-methylbutyrate (HMB) supplementation on muscle mass, function, and other outcomes in patients with cancer: a systematic review.. J Cachexia Sarcopenia Muscle, 2022.
  13. Effect of calcium β-hydroxy-β-methylbutyrate (CaHMB) with and without resistance training in men and women 65+yrs: a randomized, double-blind pilot trial.. Exp Gerontol, 2013.
  14. Effects of Beta-Hydroxy-Beta-Methylbutyrate Supplementation on Older Adults with Sarcopenia: A Randomized, Double-Blind, Placebo-Controlled Study.. J Nutr Health Aging, 2023.
  15. Oral Nutritional Supplement with β-hydroxy-β-methylbutyrate (HMB) Improves Nutrition, Physical Performance and Ameliorates Intramuscular Adiposity in Pre-Frail Older Adults: A Randomized Controlled Trial.. J Nutr Health Aging, 2021.
  16. Efficacy of beta-hydroxy-beta-methylbutyrate supplementation in maintenance hemodialysis patients.. Hemodial Int, 2017.
  17. The effects of beta-hydroxy-beta-methylbutyrate on sarcopenia in stable decompensated cirrhosis: A pilot randomized controlled trial.. Clin Nutr ESPEN, 2026.