How we grade.
We judge a supplement and a claim together, never a supplement on its own. Here’s exactly how a claim earns each verdict.
| Grade | What it takes | Listed as |
|---|---|---|
| Works | Meta-analyses of randomized trials in healthy adults show a meaningful, consistent effect. | Backed |
| Likely works | Several human trials agree, but there is no review yet or the results are mixed. | Backed |
| Unclear | Small, short or conflicting trials, or it only works in other groups. | Not backed |
| Doesn’t work | Only animal or lab studies, or good trials that found nothing. | Not backed |
The rules
- Human trials only. Rodent and test-tube results never raise a grade.
- The claim must match the trial. A result in older or deficient people doesn’t back the claim for healthy lifters.
- Effect size matters. A real but tiny effect is called tiny.
- Funding is shown. Papers with industry ties are flagged, not thrown out.
- Every verdict cites its sources. A Grade A claim must cite a meta-analysis, systematic review or position stand. The site refuses to build if one is missing.
- Safety comes first. Anything on the World Anti-Doping Agency list, or with serious safety signals, is left out.
Reading the barbell
On every supplement page, each paper is a plate on a hand-drawn bar. Taller plates are stronger study designs: meta-analyses, then systematic reviews and position stands, then single trials. Wider plates pooled more studies. The heaviest evidence sits nearest the collar. Hover a plate to preview it, tap to read it.
Questions
For each supplement we look for position stands, such as those of the International Society of Sports Nutrition, and for the most cited and most recent meta-analyses of randomized trials. Every paper is opened at the source before it is cited, and every PubMed ID is checked against PubMed automatically. Numbers on this site are the ones the papers report.
Because claims are graded separately. Creatine is backed for strength and lean mass, and not backed for fat loss. The card on each list shows only the claim that list is about.
Each page shows the date it was last reviewed. Entries are re-checked every 12 months, or sooner when a major new review comes out.