Best Supplements for Muscle Growth: Ranked by Evidence, Not by Sales

An index of the muscle supplements we have actually checked, ranked by the confidence rating we gave each one. No products named, nothing for sale. One is settled, one is real and over-prescribed, and the rest of the aisle does not survive the trials.

Most pages answering this question are shopping lists with a discount code at the bottom. This one is an index of things we have already checked, ranked by how good the evidence actually is.

No products are named and nothing here is for sale. What follows are ingredients, ranked by the confidence rating we gave them when we read the research — the same fixed four-term scale we use on everything else on this site.

The short version: one thing is settled, one is real and probably over-prescribed, and the rest of the aisle does not survive contact with the trials.

1
Creatine monohydrate
Established
It works, and it is the only one here we would call settled. Pooled across trials in adults under 50, creatine added about 2.5 lb of lean mass on top of what resistance training delivered by itself. In adults aged 57 to 70 it was closer to 3 lb. When researchers screened 250 candidate supplements against a minimum evidence standard, only two cleared it — and this was one.
2
Protein
Supported
Real, and almost certainly less than you have been told to eat. Our own verdict is about protein for fat loss rather than muscle growth specifically, and its finding is that the target most people are given is roughly a third too high. Worth reading before you buy another tub — the useful amount is a food question, not a supplement question.
3
HMB
Not checked by us
The other survivor of that 250-supplement screen — and we have not reviewed it ourselves. In the same 2003 analysis that vindicated creatine, HMB significantly increased lean mass and strength. We have not written a verdict on it, so we are not going to rank it as though we had. It is here because leaving it out would misrepresent the study we are quoting.
4
Ashwagandha
Preliminary
Something real, on a hormone — not on muscle. Pooled across 23 trials it raised testosterone in men by about 57 ng/dL. That is a measurable hormonal change and it is not the same as a demonstrated muscle-building effect. We rated it Preliminary for reasons that page sets out at length.
5
Testosterone boosters
Unsupported
The category fails, and no product in it has ever been tested. Researchers pulled the 37 ingredients out of the 32 best-selling testosterone and erectile-dysfunction supplements, found 105 randomised trials behind them, and concluded: “No whole supplement products have published RCT evidence.” Tribulus, D-aspartic acid, zinc and vitamin D are all covered there.

How this was ranked

Each entry sits at the confidence tier of the verdict behind it. Established means large, consistent evidence with the direction not in dispute. Supported means real evidence, smaller or less certain. Preliminary means something is there and nobody can tell you what yet. Unsupported means we checked and the evidence does not back the claim. Our full method is written up here.

One entry — HMB — carries no tier, because we have not reviewed it. It appears because the study that vindicated creatine vindicated HMB too, and cropping it would have made our own headline finding look tidier than it is.

Things we have not checked are not on the list. Beta-alanine, citrulline, BCAAs and caffeine all have literatures we have not read properly yet, and a guide assembled from our own verdicts cannot rank what it has not read. Padding this page with borrowed summaries would defeat the point of it.

The comparison that should end the discussion

Every creatine trial cited above tested creatine plus resistance training. Not creatine on its own. The supplement is the smaller term in that sum by a wide margin — roughly two and a half pounds of lean mass, on top of everything the training itself produced.

It is worth knowing what the training is doing, because the mechanism is not the one the supplement aisle sells. When researchers had twelve men train one arm in a bath of exercise-induced testosterone and growth hormone and the other arm with no hormone rise at all, the arm without the hormones grew slightly more. Muscle growth is driven by what happens inside the trained muscle, not by what is circulating in your blood.

Which is quietly good news, and it is the reason this page is short. There is no hormonal window to hit and no stack to optimise. There is one supplement with settled evidence, one nutrient worth getting right from food, and a great deal of training.

If you only take one thing from this page

Creatine monohydrate is the only supplement on this list we would describe as settled, and the practical questions about it are already answered: how much to take, whether it is safe, and what the weight gain actually is.

Everything else in the muscle aisle is either unproven, untested as sold, or measured and found to do nothing. We will update this page as we check more of it — and if something we ranked here turns out to be wrong, we will say so on the page rather than quietly editing it away.

Related reading: creatine benefits · do testosterone boosters work · does protein keep you full · does lifting weights burn fat · every claim we have checked

Where the ranking comes from
Every rank on this page is taken from a verdict we have already written and published, each of which carries its own sources and confidence rating. The two studies quoted directly above are Nissen SL, Sharp RL, Journal of Applied Physiology 2003;94(2):651–659, and Kuchakulla M et al., International Journal of Impotence Research 2021;33(3):311–317. Both are cited in full, with links, on the verdict pages this guide points to.