HMB Supplements: Benefits, Dosage and What the Research Really Shows
TPBy the TrustedPurchaseReview Editorial Team
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The short answer
HMB is a compound your body makes from the amino acid leucine. The strongest evidence is in older adults: two meta analyses found it helped older adults keep or gain lean mass. In younger adults doing resistance training, a 2020 meta analysis of 11 trials found no meaningful gain in muscle or strength. The International Society of Sports Nutrition (ISSN) uses a dose of 38 mg per kilogram of body weight a day, about 3 grams for a 175 lb adult, and considers HMB safe for at least one year.
HMB is sold mostly to two groups: lifters who want more muscle and adults over 40 who want to keep the muscle they have. We read the ISSN position stands from 2013 and 2025, three studies in older adults, including two meta analyses, and a meta analysis in younger adults. This guide is general information, not medical advice.
What Is HMB?
HMB, short for beta hydroxy beta methylbutyrate, is a metabolite of leucine, one of the branched chain amino acids. The 2025 ISSN position stand describes its main proposed actions as increasing muscle protein synthesis and reducing muscle protein breakdown, with possible anti inflammatory effects that may help recovery.
Supplements sell it in two forms: calcium HMB, the form used in most studies, and HMB free acid. Both are covered below.
What the Research Shows
| Study | Who and what | What it found |
|---|---|---|
| Deutz et al., Clinical Nutrition, 2013 | 24 healthy adults aged 60 to 76, 10 days of bed rest, 3 g calcium HMB a day vs placebo | The placebo group lost about 2 kg of lean mass; the HMB group did not lose a significant amount. No difference in physical function was seen, likely due to the small size |
| Wu et al., Archives of Gerontology and Geriatrics, 2015 | Meta analysis of 7 randomized trials, adults 65 and older | HMB groups gained more muscle mass than controls; no difference in fat mass |
| Lin et al., European Geriatric Medicine, 2021 | Meta analysis of 9 trials, 448 older adults | HMB increased fat free mass; HMB alone helped, but HMB added to an exercise program showed no extra gain |
| Jakubowski et al., Nutrients, 2020 | Meta analysis of 11 trials, adults 18 to 45 doing resistance training | No significant effect on lean mass, fat mass or strength compared with placebo |
| ISSN position stand, 2025 | Review of the research since its 2013 position stand | May improve body composition with training; benefits in trained athletes are mixed; may matter most in sedentary and aging people |
HMB for Older Adults
This is where the evidence is most consistent. In the Deutz bed rest study, the placebo group lost an average of 2.05 kg of lean body mass in 10 days, while the HMB group lost almost none. The authors noted the result needs a larger trial. The Wu and Lin meta analyses both found more muscle or fat free mass with HMB than without it in older adults.
One detail matters if you already exercise. In the Lin analysis, the benefit came from studies of HMB alone. When HMB was added to an exercise program, it showed no extra gain in fat free mass. The 2025 ISSN position stand reaches a similar view: HMB may be important for sedentary and aging people, while results alongside exercise vary.
HMB does not replace the basics. Protein intake and strength training still matter most; see our guide to protein and amino acids for older adults.
HMB for Younger Lifters
The 2020 Jakubowski meta analysis pooled 11 trials of adults with an average age of 27 doing resistance training. HMB added 0.29 kg of lean mass compared with placebo, a difference that was not statistically significant, and had no significant effect on strength or fat mass. The authors concluded their findings do not support using HMB to improve body composition or strength with resistance training.
The 2025 ISSN position stand is more positive: it says HMB may improve strength and power in untrained people and that results in trained athletes are mixed, looking better in studies longer than 6 weeks. If you are young, train regularly and eat enough protein, HMB is a low priority.
HMB Dosage: How Much to Take
Both ISSN position stands use a dose of 38 mg per kilogram of body weight per day. Here is what that works out to:
| Body weight | Daily HMB at 38 mg/kg |
|---|---|
| 132 lb (60 kg) | About 2.3 g |
| 154 lb (70 kg) | About 2.7 g |
| 176 lb (80 kg) | About 3.0 g |
| 198 lb (90 kg) | About 3.4 g |
| 220 lb (100 kg) | About 3.8 g |
- Splitting the dose. The Deutz study gave 1.5 g twice a day for a total of 3 g.
- Timing. Both position stands say taking HMB close to exercise may help.
- How long. The 2013 position stand found HMB most effective when started two weeks before a hard training block, and the 2025 update notes better results in athletes in studies longer than 6 weeks.
Many products provide less than these amounts per serving, so check the label.
Calcium HMB vs Free Acid
Most research used calcium HMB. According to the 2025 ISSN position stand, HMB free acid appears to raise blood levels of HMB more, but recent results are mixed. Calcium HMB also adds calcium: a product we reviewed lists 195 mg of calcium from 1,500 mg of calcium HMB, so count it if you take a calcium supplement.
Is HMB Safe?
The 2025 ISSN position stand concludes that both calcium HMB and HMB free acid are safe for oral use for at least one year, and that HMB showed no negative effect on glucose tolerance or insulin sensitivity. The 2013 position stand also described it as safe for both young and older people.
Before you start
Ask your doctor first if you are pregnant or breastfeeding, have kidney disease or take several medications. Read the full label: some muscle formulas add other ingredients, such as high dose vitamin D, that need their own safety check.
Who Should Consider HMB?
May be worth trying if you
- Are over 60 and want help keeping muscle
- Are less active, or recovering from a period of bed rest or reduced activity
- Are new to strength training
- Already eat enough protein and want an extra, researched option
Probably skip it if you
- Are young, train regularly and eat enough protein
- Expect fast or large muscle gains
- Have not yet fixed protein intake and training, which matter more
Products We Reviewed
| Product | What a serving provides | Notes |
|---|---|---|
| Advanced Muscle Plus | 1,500 mg calcium HMB (myHMB), 2,000 mg dileucine and 200 mcg vitamin D per 6 tablets | HMB is half the 3 g used in many studies; vitamin D is high. One time purchase; 90 day guarantee. Our score: 6.5/10 |
We will add more products as we review them.
HMB Label Checklist
- Grams of HMB per serving. Compare it with the dose for your body weight above.
- Form. Calcium HMB or HMB free acid; calcium HMB is the most studied.
- Servings per day. Some products need several capsules or tablets to reach one serving.
- Extras. Check added vitamin D, calcium or stimulants, and count them against what you already take.
- Claims. Be wary of promises of fast muscle gains; studies show modest effects.
FAQ
Does HMB actually work?
How much HMB should I take a day?
When should I take HMB?
Is HMB good for people over 60?
Is HMB safe?
What is the difference between calcium HMB and HMB free acid?
⭐ Our pick
If you decide to try HMB, this is the product we reviewed.
Advanced Muscle Plus 6.5/10
Calcium HMB plus dileucine for adults over 40, with every dose printed, a one time purchase and a 90 day guarantee that accepts empty bottles.
Sources
- Rathmacher JA, et al. International Society of Sports Nutrition Position Stand: β-hydroxy-β-methylbutyrate (HMB). Journal of the International Society of Sports Nutrition, 2025. Summaries: Guideline Central and NutraIngredients.
- Wilson JM, et al. International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB). Journal of the International Society of Sports Nutrition, 2013. Summary: NutraIngredients.
- Deutz NEP, et al. Effect of β-hydroxy-β-methylbutyrate (HMB) on lean body mass during 10 days of bed rest in older adults. Clinical Nutrition, 2013.
- Wu H, et al. Effect of beta-hydroxy-beta-methylbutyrate supplementation on muscle loss in older adults: a systematic review and meta-analysis. Archives of Gerontology and Geriatrics, 2015.
- Lin Z, et al. Effects of oral administration of β-hydroxy β-methylbutyrate on lean body mass in older adults: a systematic review and meta-analysis. European Geriatric Medicine, 2021.
- Jakubowski JS, et al. Supplementation with the Leucine Metabolite β-hydroxy-β-methylbutyrate (HMB) does not Improve Resistance Exercise-Induced Changes in Body Composition or Strength in Young Subjects. Nutrients, 2020.
About the editorial team
Written by the TrustedPurchaseReview editorial team. We read official labels and sales pages and check them against published research and government sources. We do not buy or test the products ourselves. We earn affiliate commissions on some links, and ratings are not for sale.
Questions or corrections? Contact us.
This guide is informational and not medical advice. Talk to your doctor before starting supplements, especially if you have a medical condition.