β-hydroxy β-methylbutyrate (HMB) has become a popular supplement among athletes and bodybuilders seeking muscle mass and strength. But does the scientific evidence actually support using HMB for these goals? Let’s take an in-depth look at what the research says.
How HMB Works in the Body
HMB is a metabolite of the branched-chain amino acid leucine. After leucine is metabolized into HMB, HMB appears to have several effects that could potentially promote muscle growth, including:
- Increasing protein synthesis rates in muscle cells
- Reducing muscle protein breakdown
- Activating muscle growth pathways like mTOR
- Reducing muscle damage from exercise
These mechanisms suggest HMB supplementation coupled with strength training could increase muscle mass and strength gains compared to training alone. But what do the human studies show?
HMB (Hydroxy Methyl Butyric acid) is a compound that helps support protein synthesis and lean muscle retention, especially when eating at a caloric deficit. This product from Double Wood contains 120 capsules with 500mg HMB per capsule.
HMB Research Findings for Muscle Growth
Several research reviews and meta-analyses have compiled the results of all the quality studies on HMB and muscle growth:
- A meta-analysis in Nutrients looked at 11 studies on HMB. It found HMB groups gained an extra 0.34 kg (0.75 lbs) of body weight and 0.4 kg (0.88 lbs) more lean mass compared to placebo groups after 6-12 weeks of training.
- A review in the Journal of the International Society of Sports Nutrition analyzed 7 studies on HMB. It reported volunteers who took HMB gained an average of 0.28 kg (0.6 lbs) more lean body mass than those who took placebo.
- A meta-analysis in the British Journal of Sports Medicine examined 9 studies on HMB. It found HMB produced small increases in fat-free mass gain of 0.28 kg (0.6 lbs) compared to placebo.
Based on these analyses, supplementation with HMB does appear to provide a small beneficial effect on lean muscle mass gains during training. However, the extra amount of muscle gained is relatively small, averaging around 0.3-0.4 kg (0.6-0.9 lbs) over 6-12 weeks.
This suggests HMB is not a muscle-building miracle supplement. The gains associated with HMB are minor compared to what can be achieved naturally through proper strength training and nutrition. However, some people may still find value in the small additional boost HMB provides.
HMB for Increasing Muscle Strength
In addition to muscle growth, some studies have examined whether HMB improves strength development during training:
- The Nutrients meta-analysis found no significant difference in strength gains between HMB and placebo groups.
- The Journal of the International Society of Sports Nutrition review also concluded HMB does not substantially increase strength compared to placebo.
- The British Journal of Sports Medicine meta-analysis determined gains in upper and lower body strength did not differ between HMB and control groups.
Overall, the scientific research suggests HMB supplementation provides minimal to no additional benefit for improving muscle strength during a resistance training program. This aligns with the small effects seen for HMB on muscle growth.
Optimal HMB Dosage for Muscle Growth
Most studies finding benefits of HMB supplementation for muscle gain and strength have used a dosage of 3 grams per day. Lower doses under 2 grams per day are less effective, while more than 3 grams per day provides no additional advantage.
Three grams per day, or 1 gram taken thrice daily, appears to be the ideal HMB intake for those looking to maximize potential muscle-building effects. Exceeding 3 grams per day will only increase the cost of supplementation without any added benefit.
Should You Take HMB for Muscle Building?
Here are some key takeaways when weighing whether HMB is worth taking as a muscle-building supplement:
- The average gain in lean muscle mass associated with HMB is small, around 0.3-0.4 kg (0.6-0.9 lbs) over a 6-12 week training period. However, some people may still find value in these minor additional gains.
- An HMB dosage of 3 grams daily, split into three doses, is ideal for maximizing benefits. More than this dosage has no added advantage.
- HMB provides only a mild muscle-building advantage in addition to a proper training and nutrition program. While some may supplement with HMB, it is unnecessary for significant muscle gains.
In summary, HMB can provide a small boost in lean muscle growth over the course of a training program. However, gains directly attributable to HMB tend to be minor. Taking HMB can certainly help, but it likely isn’t the miracle muscle pill you were hoping for.