HMB, short for beta-hydroxy-beta-methylbutyrate, is a metabolized form of an amino acid that’s used to promote muscle growth and strength gains in weightlifters and athletes.
It helps promote both strength and muscular growth by preventing the breakdown of protein in your body. In this way, it assists in maintaining what physiologists call “positive protein balance”: your body is gaining more protein than it’s losing.
When this happens, you put on muscle mass and you get stronger. If that sounds like a good outcome for you, check out our rankings of the best HMB supplements on the market. These supplements will help you get both bigger and stronger.
Research
Rankings
1. Optimum Nutrition HMB
Optimum Nutrition is king when it comes to bodybuilding and weightlifting supplements. This company is widely known for its excellent protein and amino acid products, and its HMB supplement lives up to the same standards.
It’s very pure, and delivers 1000 mg of HMB per capsule. The capsules are made of gelatin, which will only be a problem for the strictest of vegetarians.
2. MET-Rx HMB 1000
MET-Rx makes an incredibly popular HMB supplement that delivers 1000 mg of HMB per serving in a gelatin capsule. The design is fairly clean, though some purists would prefer a cellulose capsule or the lack of silica.
Despite this, it’s widely applauded for its ability to assist with muscular gains, both in terms of size and actual strength.
3. Double Wood Supplements HMB
Double Wood Supplements HMB wins points for using third-party testing to ensure purity, though athletes looking for optimal doses will be frustrated by the lower than average dosage (500 mg per capsule).
This means you’ll go through a bottle a lot quicker than you would in a higher dose supplement. Other than HMB, the only additional ingredients are rice flour and gelatin (for the capsule), making this a very pure supplement despite its low dosage.
4. Vitamonk HMB
Vitamonk HMB is a good option for vegetarians and vegans thanks to its use of a cellulose capsule and its pure supplement design.
While there are better supplements out there, they all use animal-derived gelatin in their capsule. The major downside with this HMB supplement is that each capsule only contains 500 mg of HMG, so you’ll go through a bottle pretty quickly.
5. Bulksupplements Pure HMB powder
Bulksupplements makes a solid loose powder form of HMB, but given that the effective dose fairly low (compared to something like whey protein powder) it’s going to be challenging for you to get the right amount of HMB every day, unless you’ve already got a scale that’s accurate to the milligram.
The plastic bag is also liable to cause a bit of a mess when you try to reseal it after use. That aside, if all you want is pure HMB with no additives and no capsule, this is definitely the way to go.
6. Nutricost HMB
Nutricost HMB is a pretty basic moderate-dose HMB supplement. It comes in 500 mg capsules, so the dosage per capsule is lower than some of its higher-ranked competitors. Ingredients-wise, though, it’s formulated pretty clean, so it’s a solid choice if you know you want a lower-dose capsule-based source of HMB.
7. AMRAP Nutrition Certified HMB Capsules
AMRAP Nutrition makes an HMB capsule that’s a middle of the road dosage: 750 mg per capsule.
While this is an acceptable dosage range for many people, the real problem is that there aren’t very many capsules per bottle, so you’ll go through this supplement pretty quickly.
That’s even more true if you are using this convenient dosage to hit 1500 mg of HMB per day.
8. Blonyx HMB+ Creatine
Blonyx provides HMB alongside creatine monohydrate, which is one of the most effective and tested supplements for increasing muscle strength and muscle mass.
Both are provided at efficacious doses, so if you are looking to combine the benefits of both supplements, Blonyx makes it easy by putting them both in one package.
The powder form means you can adjust the dosage to fit your current needs, which is especially important with creatine since most dosing protocols involve a “loading” phase with a higher dose, followed by a moderate-dose maintenance phase.
9. Bodytech HMB + Vitamin D3
Bodytech blends HMB with both calcium and vitamin D3, making it a decent supplement for people looking to boost muscle strength and bone strength at the same time. The primary downside is that the vitamin D dosage is not that high: only 333 IUs per serving.
10. NutraKey HMB
NutraKey makes a pretty simple HMB supplement, but the big downside is dosage. At only 333 mg per capsule, it’s one of the lowest dose HMB supplements out there.
Even though it does have a pretty clean supplement design with no unnecessary additives, the dosage is low enough that even smaller people (who would likely want a lower dosage anyways) are liable to find the dosage too low.
Category winners
Best HMB overall: Optimum Nutrition HMB
Optimum Nutrition takes our top spot overall in the rankings thanks to its high-dosage formulation and lack of any additives or secondary ingredients. These two features make it a versatile and flexible HMB supplement that’s suited for just about any use case.
Best HMB for athletes: Optimum Nutrition HMB
Since building strength, speed, and power is one of the main applications of HMB, it should be no surprise that our top overall HMB recommendation is also our recommendation for athletes.
Best HMB for burning fat: Double Wood Supplements HMB
The lower dosage of Double Wood HMB is good for dieters and others looking to burn fat while maintaining muscle mass: by taking a lower dosage spread throughout the day, you can sustain the strength-preserving effects of HMB during longer periods of dieting.
Best powder-form HMB: Bulksupplements Pure HMB powder
Looking to mix up your own protein shakes fortified with HMB? Bulksupplements is our recommendation, thanks to its pure formulation and ease of use. If you want to mix up a custom combination of HMB and other useful muscle building supplements like creatine, BCAAs, and beta-alanine, Bulksupplements is the way to go.
Best HMB with creatine: Blonyx HMB + Creatine
HMB and creatine are a potent combo for increasing muscle mass and power. For this application, we recommend Blonyx HMB+Creatine, which combines creatine monohydrate and HMB in a 5:3 ratio. Since it’s a powder form supplement it’s easy to adjust it for either creatine loading or maintenance.
Best HMB for gaining mass: Optimum Nutrition HMB
If you are intent on bulking up, Optimum Nutrition HMB is a safe bet. These high dose capsules make it easy to double or triple your dosage if necessary as part of your bulking routine. The lack of additional active ingredients also means it combines well with other mass-gaining supplements, so you don’t have to worry about any interactions with the rest of your supplement stack.
Who should buy HMB?
HMB is safe for most individuals looking to improve muscle mass, performance and strength. It is also great for people looking to stop unwanted weight loss during periods of stress or disease.
Pregnant and breastfeeding women should not use HMB since it is not well studied in these populations. While there are no serious medication interactions, you should speak to your doctor before taking an HMB supplement if you are currently taking any prescription medication.
How we ranked
When ranking the best HMB supplements, we first looked at the delivery method. Powder-based HMB seems like a better choice on the surface since it tends to be cheaper and contains fewer fillers. However, given the not-so-pleasant taste of HMB, we preferred capsule-based products like Met-Rx and VitaMonk. This being said, we still allowed some powders on our list as long they were of the highest quality and purity, like Bulk Supplements.
We also looked at added ingredients. While pure HMB was excellent, we did have a slight preference for products that used complementary ingredients to support the benefits of HMB. Lastly, we looked at the dosage. According to research, the clinically effective dosage of HMB is between 2-3g. We had a preference for slightly lower dosed products, like Optimum Nutrition, as this allowed for more tailoring and titration with new users.
Benefits
HMB can help increase muscle mass and muscular strength. The best evidence for the muscle-boosting power of HMB comes from a randomized and placebo-controlled clinical trial published in 2014 in the European Journal of Applied Physiology (1).
The study, performed by researchers at the University of Tampa and Iowa State University, involved eight weeks of standard weight training, a two-week “overreaching” period where the subjects trained harder than usual, and a two-week taper at the end.
Half of the subjects were randomly assigned to take an HMB supplement (taken at a dose of 3 grams per day) while the other half received a placebo.
The results showed that the HMB supplement was associated with an increase in total strength (defined as the sum of bench press, squat, and deadlift one rep maximum) as well as an increase in lean body mass.
This means that your muscle mass increase thanks to HMB is functional, i.e. it’s a true increase in muscular cross-sectional area, which contributes directly to muscular strength.
HMB can prevent performance losses during periods of overreaching and overtraining. One of the most interesting aspects of the study above was what happened during the two-week period of overreaching.
The subjects who were taking the HMB supplement experienced an attenuated increase in the hormonal markers of overtraining when compared to the control group. Creatine kinase and cortisol levels, which rise when the body is in an overstressed and catabolic state, did not increase as much in the HMB group compared to the placebo group.
A review study published in 2008 in the journal Nutrition & Metabolism provides a potential explanation—HMB is involved in inhibiting a biochemical pathway associated with muscle breakdown (2).
So, at least according to this hypothesis, HMB can extend your ability to train hard and limit the muscle breakdown that happens during periods of intense training, even if they are a bit beyond your current capabilities.
That being said, it shouldn’t be used as an excuse to overtrain—you might be able to push a bit beyond the physical limitations of your body with HMB, but you’re still subject to going too far if you completely disregard intelligent training protocols.
HMB works equally well in men and women. Some supplements for strength gain might work better in men, because their core function is to boost testosterone or growth hormone levels, and men have a higher ceiling when it comes to these hormones.
HMB, however, works through a different pathway. A study conducted by researchers at East Tennessee State University tested the effects of HMB on increasing upper body strength in 39 men and 36 women (3). The subjects were randomly assigned either a three gram per day dose of HMB or a placebo, and the researchers tracked strength gains over the course of four weeks.
In addition, the researchers tested to see if there was a difference in strength and muscle mass gains between the men and the women. They found that HMB worked equally well for both groups, leading to increases in upper body strength and lean body mass.
This finding is especially promising for female power athletes, since it means they’ll get the same level of benefit as men.
HMB could decrease your risk of cardiovascular disease. While HMB’s reputation is mostly as a performance aid for athletes looking to gain muscular strength, there’s emerging evidence it could be helpful for reducing your risk of cardiovascular disease as well.
Given that overall strength and fitness is protective for your heart, this might not be so surprising, but it’s rewarding to know nevertheless.
A scientific study published in the Journal of Nutrition in 2000 cataloged the potential heart health benefits of HMB by conducting a series of studies on human subjects ranging from three to eight weeks in duration (4).
The researchers examined a wide range of biochemical, physical, and psychological measures of health, and found that three markers of heart health were consistently improved on HMB: the supplement resulted in a decrease in total cholesterol, a decrease in LDL (“bad”) cholesterol, and a decrease in systolic blood pressure.
Increasing muscle mass and decreasing fat mass has a similar effect, and although significant changes in these variables were not observed, the same biochemical pathways might have been activated, accounting for the improvements.
Side effects
Several large placebo-controlled clinical trials of HMB have been conducted (several of which were described above), and none have reported significant adverse effects associated with HMB.
This might be because HMB is just a metabolized form of the branched chain amino acid leucine, which is found in copious quantities in foods like nuts, chicken, and cheese.
As long as you stay within the bounds of usual dosages, there appear to be no immediate risks associated with taking HMB (higher doses aren’t bad; they just haven’t been studied).
Because it’s been studied primarily for its short-term athletic benefits, there isn’t as much research on the chronic effects of HMB, so we don’t have information on how it might affect your body if you take it over the course of many years.
Despite this caveat, HMB is one of the safest supplements out there for augmenting your strength gains at the gym.
Recommended dose
The vast majority of research on HMB uses daily doses of three grams per day. This dose seems to be universal for men, women, as well as different body types, but as with other supplements for increasing strength, large athletes might need to take more and small athletes might need to take less.
To maintain as consistent of a level of HMB in your body as possible, it’s probably best to space out your doses equally throughout the day. For example, you could take one gram in the morning, afternoon, and evening.
FAQ
What is HMB, and what does it do? HMB stands for hydro-methyl butyrate, which is naturally produced in the body when you break down the amino acid leucine. One study describes HMB as both anabolic and anti-catabolic, which means that it helps to build lean muscle mass and prevent the loss of lean body mass.
The same study also found that HMB helped patients experience increased benefits from rehabilitative exercises after an injury, as well as improve cognition, decrease abdominal obesity, and support bone density (5). This makes HMB useful for dedicated athletes, new gym-goers looking to prevent injury, and older individuals who are seeking to improve their health.
Is HMB an amino acid? Proteins are made up of amino acid chains, which the human body breaks down and digests into individual amino acids. These amino acids are then used as the building blocks of cells. To build or maintain muscle, your body needs a full spectrum of the 20 amino acids and adequate protein intake.
Of these 20, nine cannot be produced within the human body and need to be obtained from food (6). These are called essential amino acids, as their presence is essential to the human diet. HMB is not considered an amino acid. Rather it’s a by-product of the amino acid leucine when it is broken down in the body.
Are leucine and HMB the same thing? Leucine is one of the nine essential amino acids and is a metaphorical delivery man with a side job as a protector. This multi-talented amino acid helps the human body synthesize and use other amino acids. It helps deliver essential amino acids, or cellular building blocks, to parts of the body that need it most, while also blocking the degradation of existing muscle tissue.
Your body uses most of its leucine in the process of muscle building. However, in order to better build muscle, leucine breaks down even further into ketoisocaproate and hydro-methyl butyrate, or HMB. HMB can help your body more efficiently synthesize protein and speed up the delivery of leucine to skeletal muscle.
Why are leucine and HMB important for exercise? Exercise causes your body to change how it uses protein and leucine is the amino acid that is most affected by exercise-induced changes in protein and amino acid metabolism. As your body’s amino acid delivery system, it’s working over-time.
It operates side-by-side with insulin to help your cells signal to the rest of your body that they need more energy and protein to get stronger. In this exercise-induced signaling and rebuilding process, HMB helps your body adjust more rapidly to exercise-induced needs.
Is HMB a useful supplement if I don’t exercise? HMB is associated with health benefits in sedentary populations. One study found that HMB helped older adults combat malnutrition and lean tissue loss associated with aging (7). By helping to increase the efficiency of protein synthesis, HMB encourages the body to retain lean mass.
However, exercise is by far the most effective single method for gaining lean mass and delaying or reversing frailty. Exercise is also associated with a host of other wellness benefits, including lowered blood pressure, improved cognition, enhanced mood, better sleep rhythms, and protection against neurodegenerative disease.
If it is safe for you to exercise, use HMB to complement and compound the benefits of physical activity, rather than replace it. If you are limited in your ability to exercise, HMB may help you prevent atrophy and protect the functionality you currently possess. HMB also may help decrease LDL cholesterol and blood pressure, but more research is needed to determine the exact mechanisms for this process (8).
How is HMB absorbed in the body? The human body absorbs HMB, much like it absorbs other amino acid compounds. Dietary proteins are broken down into amino acids in the small intestines, where they are absorbed. For this reason, some autoimmune diseases and gastrointestinal disorders can interfere with protein absorption and lead to malnutrition. If you feel that your body isn’t absorbing nutrients or protein the way that it should, consult your healthcare provider.
What’s the best way to take HMB? Most HMB users take HMB 30-60 minutes before a workout or physical therapy session in order to maximize muscle performance and recovery. By increasing the bioavailability of leucine before a workout, your body can use amino acids to prevent muscle damage and replenish your energy stores (9).
HMB is available in tablet or powder form. The best option for you depends on whether you want the convenience of a tablet or want to mix your HMB with another protein or nutrient shake. The powder can taste weird to some people, so it works better when mixed with juice.
What if I cannot take HMB before exercise? While not ideal, your body can still enjoy the benefits of HMB after exercise if taken within an hour after you finish working out.
Can I take HMB both before and after exercise, and can I use it on my off days? Research suggests that you can take HMB both before and after exercise to enhance recovery, so long as you stay within a safe and doctor-recommended dosage range. This is because HMB increases the availability of substrate for cholesterol synthesis within skeletal muscle, which may be able to help your body at every stage of the repair process (10).
You may find that incorporating HMB on your off days helps to alleviate symptoms of delayed-onset muscle soreness. Though more studies are necessary before these findings are deemed conclusive, it may also help prevent injury when incorporated into your off-day wellness regimen.
Is HMB bad for you? According to a recent study, no adverse side effects have been found in either animal or human HMB trials. The same study also details that HMB might have varying effectiveness for different stages in life, but more research is needed to determine this exactly (11).
How often should I work out to build muscle with HMB? Although HMB may help your body repair itself more quickly after workouts, users should continue their usual workout routine and not push their limits or intensify their workouts without advice from a doctor. Between 150 and 300 minutes of moderate-intensity exercise per week is sufficient for most adults.
Research has established that adults over 45 should not work out more than 300 minutes per week, and all individuals should take at least one day off from working out each week. Over exercise may be associated with an increased risk of coronary artery disease, malignant ventricular arrhythmias, and atrial fibrillation.
Can HMB improve stamina? HMB does not immediately improve stamina or energy, but it can improve the overall condition of the muscles; so there may be some long-term effects on stamina. Some studies have shown promising effects on endurance over periods as long as 12 weeks, especially in athletes, but there is no solid research yet on overall aerobic capacity improvement due to HMB (15).
How much HMB should I take? The recommended dose for HMB, regardless of body size or weight, is 2-3 grams per day split between multiple 1-gram doses. Though some studies have also investigated smaller doses, 3 grams per day has been well-researched as a safe and possibly effective dose. Higher doses may be possible under a doctor’s supervision.
Can you overdose on HMB? Overdosing on HMB may have negative effects on protein synthesis in the kidneys, colon, heart, and spleen. The exact threshold for an overdose has not been determined yet, so users must consult with a doctor before taking more than 3 grams per day.
Does HMB affect mood? Unlike steroids, there is no evidence that HMB negatively affects mood. However, the effects of supplements and medications may interact in unpredictable ways. A doctor can help you decide if you are at risk for mood-related side effects due to an existing mood disorder or medication interactions.
Is HMB safe for pregnant women? There have been no research-backed investigations into the safety of HMB for pregnant or nursing women. Pregnant and nursing women should avoid HMB unless specifically instructed by a doctor.
Is HMB safe for minors and seniors? Minors under 18 should not take supplements like HMB unless instructed by a doctor. Seniors may take HMB in conjunction with an exercise plan prescribed by a doctor. One small study determined that HMB was just as effective in a 70-year-old cohort as it is in young adults (16).
Can diabetics take HMB? Muscles, protein, and insulin interact in complex ways, which makes it difficult for individuals for diabetes to take fitness supplements. Diabetics should consult with a doctor before starting a new fitness plan or taking HMB.
Where can I buy HMB? HMB supplements are available online and at certain brick-and-mortar stores that specialize in fitness supplements. However, shopping online gives you a larger selection of products and easy access to user reviews so you can determine the right supplement for you. Two of our favorite products, Forge by Legion Athletics and Optimum Nutrition HMB can be found on Amazon.
Can HMB powders or tablets expire? Some HMB products can expire, and while they may still be safe to consume, their effectiveness may be reduced. Always replace products that are past their use-by date, and powders should be replaced six months after they have been opened.
Why do athletes use HMB? HMB increases muscle mass and muscular strength by preventing protein breakdown. It’s a metabolized form of the amino acid leucine, and thanks to some specific biochemical actions, when taken in supplemental form it allows you to take advantage of all the benefits of strength training. If you want a supplement that helps you make the most of your hard work in the weight room, HMB might be just what you’re looking for.
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Recap
HMB is a supplement that’s been consistently found to improve muscular strength and increase lean body mass. It works through different pathways than other supplements for increasing strength; its primary function seems to be the prevention of muscle breakdown.
For this reason it works equally well in men and women, and it seems particularly well-suited for protecting your body during periods of heavy training.
Some research even suggests that HMB could help decrease cholesterol and blood pressure, making it useful for reducing your risk of cardiovascular disease.
When taken at the recommended dose of three grams per day, it’s a safe and effective way to get more lean body mass and more strength.
For BodyNutrition’s #1 recommended HMB supplement, click here.
