HMB
β-Hydroxy β-Methylbutyrate
Leucine metabolite that helps prevent muscle breakdown and supports recovery, especially during caloric restriction or intense training.
HMB is a metabolite of the amino acid leucine. Its primary benefit is reducing muscle protein breakdown rather than increasing protein synthesis. Most effective for preventing muscle loss during caloric deficits, in older adults, or during very intense training periods. Benefits are more modest in well-trained individuals eating adequate protein.
Mechanisms of Action
Anti-Catabolic
Slows muscle protein breakdown
Cell Membrane Support
Supports muscle cell membrane integrity
Recommended Dose
3g daily
Optimal Timing
- Split into 1g doses 3x daily
- Or all at once with a meal
Take with food
Best Form
HMB-Ca (calcium salt) capsules or powder
Alternatives: HMB-FA (free acid) — faster absorption
HMB-FA absorbs faster and may be better pre-workout. HMB-Ca is more affordable and works well for daily use.
Duration
Minimum: 2 weeks
Optimal: 4 weeks
Cycling: Not required
Note: HMB-FA (free acid form) can be taken pre-workout for acute effects. HMB-Ca (calcium salt) is more common and can be taken anytime.
Personalized Dosage Calculator
Get a dosage recommendation tailored to your body weight, age, goals, and health profile.
Set up your health profile for personalized recommendations
Reduced Muscle Loss
Preserves muscle during dieting or overtraining
Faster Recovery
Less soreness and faster strength recovery
Insufficient data; avoid supplementation
May be particularly beneficial for preserving muscle mass
Who Should NOT Take This
- Known allergy or hypersensitivity to HMB or related compounds
Drug Interactions
Generally safe to combine with other supplements and medications
Possible Side Effects
Tip: Take with food
Warnings
- Benefits most pronounced in untrained individuals, during caloric restriction, or in older adults
- Well-trained athletes on adequate protein may see minimal benefits
Top studies from 40+ peer-reviewed papers
Moore ZE et al. • The Cochrane database of systematic reviews (2020)
“Evidence for the impact of nutritional interventions on the healing of foot ulcers in people with diabetes compared with no nutritional supplementation, or compared with a different dose of nutritional supplementation, remains uncertain, with eight studies showing no clear benefit or harm.”
Key Findings:
- It is also uncertain whether arginine, glutamine and β-hydroxy-β-methylbutyrate supplement increases the proportion of ulcers healed at 16 weeks compared with placebo (RR 1.09, 95% CI 0.85 to 1.40).
- It is uncertain whether oral nutritional supplement with 20 g protein per 200 mL bottle, 1 kcal/mL, nutritional supplement with added vitamins, minerals and trace elements, reduces the number of deaths (RR 0.96, 95% CI 0.06 to 14.60) or amputations (RR 4.82, 95% CI 0.24 to 95.88) more than placebo.
- It is uncertain whether arginine, glutamine and β-hydroxy-β-methylbutyrate supplement increases health-related quality of life at 16 weeks more than placebo (MD -0.03, 95% CI -0.09 to 0.03).
- It is also uncertain whether arginine, glutamine and β-hydroxy-β-methylbutyrate supplement reduces the numbers of new ulcers (RR 1.04, 95% CI 0.71 to 1.51), or amputations (RR 0.66, 95% CI 0.16 to 2.69) more than placebo.
Bear DE et al. • The American journal of clinical nutrition (2019)
“HMB, and supplements containing HMB, increased muscle mass and strength in a variety of clinical conditions, although the effect size was small.”
Key Findings:
- Effect sizes were small.
- No effect on bodyweight (SMD = 0.16; 95% CI: -0.08, 0.41; z = 1.34; P = 0.18; I2 = 67%) or any other outcome was found.
- HMB, and supplements containing HMB, increased muscle mass and strength in a variety of clinical conditions, although the effect size was small.
- Given the bias associated with many of the included studies, further high-quality studies should be undertaken to enable interpretation and translation into clinical practice.
Comishen KJ et al. • Journal of thrombosis and haemostasis : JTH (2025)
“Many diagnoses were associated with bleeding disorders and, therefore, warrant investigation when assessing a patient with HMB of unknown etiology.”
Key Findings:
- The overall prevalence of bleeding disorders was 30% (95% CI, 14-46); von Willebrand disease, 8% (95% CI, 7-10); platelet function defect, 9% (95% CI, 7-12); abnormal thyroid, 3% (95% CI, 0-6); and polycystic ovarian syndrome, 8% (95% CI, 4-12).
- Subgroup analysis showed bleeding disorders were prevalent in 16% (95% CI, -8 to 41) of adults with HMB but in 39% (95% CI 18-60) of adolescents with HMB.
- Many diagnoses were associated with bleeding disorders and, therefore, warrant investigation when assessing a patient with HMB of unknown etiology.
- The causes are likely age dependent and should be considered when diagnosing HMB.
Harlow J et al. • Nutrients (2024)
“Nutrition supplementation may have small benefits on muscle performance and recovery in warfighters.”
Key Findings:
- Nutrition supplementation may have small benefits on muscle performance and recovery in warfighters.
- However, there are significant limitations in interpretation due to the largely inconsistent evidence of ingredients and comparable outcomes.
- Thus, there is inadequate practical evidence to suggest how dietary supplementation may affect field performance.
Vitale SG et al. • Medicina (Kaunas, Lithuania) (2022)
“However, such findings need to be confirmed by additional trials due to the high number of outdated studies and recent improvements in hysteroscopic instrumentation and techniques.”
Key Findings:
- Relative to uterine balloon therapy, amenorrhea was more common with EA/GER (relative risk 1.51 [95% CI 1.03 to 1.20] I2 = 28%), but posttreatment satisfaction was similar.
- Anxiety, depression scores and complication rates were similar between treatments.
- Conclusions: Women's perception of QoL might be seen to be less improved after hysteroscopic ER/GEA rather than hysterectomy.
- However, such findings need to be confirmed by additional trials due to the high number of outdated studies and recent improvements in hysteroscopic instrumentation and techniques.
Study Type Distribution
Goals This Supplement Supports
Related Goals
This information is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider before starting any supplement.