tuneTypical Dose
3
Supplement
HMB
beta-hydroxy-beta-methylbutyrate
Evidence TierBWADA NOT PROHIBITED
watchEffect Window
~6-12 weeks for meaningful lean mass/strength signal. Shorter windows may still show recovery marker changes.
check_circleCompliance
WADA NOT PROHIBITED
Overview
Clinical Summary
HMB is a small molecule, salt, or polymer used for targeted metabolic or digestive effects. It is used to influence specific pathways rather than general nutrition.
Evidence varies widely by compound. Some have controlled human data for specific outcomes such as lipid markers, glycemic response, or symptom relief, while others are supported mainly by mechanistic studies. Minority uses include inflammation modulation and antioxidant effects. Dose, formulation, and safety constraints often determine whether measurable benefits occur.
Supports protein turnover and may reduce exercise-related muscle-damage signaling in human and translational studies.
Outcomes
What This Is Expected To Influence
Primary Outcomes
- Increase/maintenance of lean body mass
- Improved resistance-based strength outcomes
Secondary Outcomes
- Reduced exercise-induced damage markers (CK/LDH)
- Modest reduction in abdominal adiposity with RT
Safety
Contraindications and Interactions
Contraindications
- Severe renal/hepatic impairment
- Severe unstable cardiometabolic disease
- Pregnancy/lactation without clinician oversight
- Active unexplained severe GI intolerance
Side effects
- Itching
- Abdominal pain
- Upset stomach and heartburn
- Constipation
- Nausea
- Flatulence
- Headache
- Transient fatigue
- Increased blood pressure
Interactions
- Limited data on significant interactions at standard dose
- Use caution with medications that substantially affect renal clearance or metabolic load
- Avoid adding other high-dose anabolic or metabolic supplements during initial assessment
- Potential overlap with intensive multi-supplement performance stacks
Avoid if
- Active liver disease
- Severe renal impairment
- Significant medical instability
- Known severe GI hypersensitivity
- Pregnancy/lactation without clinician oversight
Evidence
Study-level References
hmb-SRC-001Meta-analysis (21 RCTs)
Sourceopen_in_newPMID:40248035
Population: Adults >50 years
Dose protocol: ~3 g/day in many pooled studies. Duration analyses included >6 to 12+ weeks.
Key findings: Improves appendicular lean mass, handgrip strength, gait speed.
Notes: Heterogeneous populations and products. Large pooled sample increases power but limits precision for subgroups.
Paper content
Improves appendicular lean mass, handgrip strength, gait speed.
hmb-SRC-002Umbrella review of meta-analyses
Sourceopen_in_newPMID:39797501
Population: Adults 23-79 years across prior meta-analyses
Dose protocol: Synthesized published HMB interventions
Key findings: Small-to-moderate improvements in muscle mass and strength. Limited effect on fat mass/body mass.
Notes: Variable study quality. Umbrella-level synthesis includes heterogenous primary designs.
Paper content
Small-to-moderate improvements in muscle mass and strength; limited effect on fat mass/body mass.
hmb-SRC-003Randomized controlled trial
Sourceopen_in_newPMID:25700845
Population: 48 healthy older men (66-78 years), 12-week intervention
Dose protocol: HMB + resistance training vs comparators
Key findings: RT + HMB reduced abdominal fat mass compared with RT alone/placebo conditions.
Notes: Good randomized design. Older sample with modest sample size.
Paper content
RT + HMB reduced abdominal fat mass compared with RT alone/placebo conditions.
hmb-SRC-004Randomized controlled trial
Sourceopen_in_newPMID:23514626
Population: Healthy older adults during 10-day bed rest
Dose protocol: HMB during bed rest + post-bed-rest resistance rehabilitation
Key findings: Attenuated lean mass decline in HMB arm.
Notes: Confirmatory finding is clinically relevant but sample size is small.
Paper content
Attenuated lean mass decline in HMB arm.
hmb-SRC-005Safety synthesis across 9 studies
Sourceopen_in_newPMID:10917905
Population: Adults 3-8 weeks, mixed sex and age, exercise and non-exercise cohorts
Dose protocol: 3 g/day HMB
Key findings: No meaningful adverse safety signal. Suggested lipid and BP improvements in pooled data.
Notes: Safety outcomes are supportive but not powered for rare events.
Paper content
No meaningful adverse safety signal; suggested lipid and BP improvements in pooled data.
hmb-SRC-006Meta-analysis
Sourceopen_in_newPMID:29676656
Population: Adults with exercise-induced muscle damage protocols
Dose protocol: HMB supplementation, subgroup by duration (<6 weeks vs >=6 weeks)
Key findings: Reduced CK and LDH, stronger effect with 6+ week use.
Notes: Marker outcomes are robust and pooled but not direct performance endpoints.
Paper content
Reduced CK and LDH, stronger effect with 6+ week use.
hmb-SRC-007Randomized controlled trial
Sourceopen_in_newPMID:19387396
Population: 22 resistance-trained men, 9 weeks
Dose protocol: 3 g/day HMB + resistance training
Key findings: Clear advantage for lower-body strength only. Body composition effects largely inconclusive.
Notes: Real-world trained-athlete sample with limited size and context specificity.
Paper content
Clear advantage for lower-body strength only; body composition effects largely inconclusive.
hmb-SRC-008Systematic review and meta-analysis of randomized controlled trials.
Sourceopen_in_newGarcia-Alonso N, Sanchez-Gonzalez JL, Navarro-Lopez V, Mendez-Sanchez R, Polo-Ferrero JM. The Role of HMB Supplementation in Enhancing the Effects of Resistance Training in Older Adults: A Systematic Review and Meta-Analysis. Nutrients. 2025;17(22):3624. doi:10.3390/nu17223624. PMID:41305674.
Population: Older adults participating in resistance training interventions across 10 RCTs (n=596).
Dose protocol: HMB combined with resistance training across 10 RCTs (n=596 older adults)
Key findings: Modest handgrip strength improvement (SMD 0.24) and moderate SPPB improvement (SMD 0.54). No significant lean mass or body composition effects.
Notes: Important nuance. When HMB is added to active resistance training, the incremental benefit is functional rather than compositional.
Paper content
This meta-analysis pooled 10 RCTs (n=596) examining HMB combined with resistance training in older adults. It found modest improvements in handgrip strength and moderate improvements in physical performance battery scores. Notably, it did not find significant effects on appendicular lean mass, gait speed, muscle quality, fat mass, or body weight. This contrasts somewhat with earlier meta-analyses that reported lean mass benefits, suggesting that when HMB is added to an already-active resistance training program, the incremental benefit is primarily functional rather than compositional.
hmb-SRC-009Randomized, double-blind, placebo-controlled crossover trial.
Sourceopen_in_newRamos-Hernandez R, Mielgo-Ayuso J, Fernandez-Lazaro D, et al. Creatine plus beta-Hydroxy-beta-Methylbutyrate supplementation is associated with preserved glutathione redox-balance and redox-function associations in older adults. Biogerontology. 2026. doi:10.1007/s10522-026-10407-2. PMID:41712056.
Population: 30 physically active older adults (mean age 62.7 years, 20 men, 10 women).
Dose protocol: 3 g/day calcium HMB plus 3 g/day creatine versus placebo, two 6-week crossover phases
Key findings: Preserved glutathione redox balance during supplementation phase compared with placebo.
Notes: Mechanistic biomarker study. Adds antioxidant-defense dimension to HMB evidence but not a clinical outcome trial.
Paper content
This double-blind crossover RCT tested creatine (3 g/day) plus calcium HMB (3 g/day) versus placebo over two 6-week phases in 30 physically active older adults doing supervised exercise. The combination attenuated the placebo-related increase in oxidized glutathione, suggesting preserved redox balance. This is a mechanistic biomarker study rather than a clinical outcomes trial, but it provides novel evidence that HMB combined with creatine may support antioxidant defense in exercising older adults. The crossover design strengthens internal validity despite the modest sample size.