What is FFMI, and what counts as a natural FFMI?

FFMI is fat-free mass in kilograms divided by height in metres squared, normalized to 1.80 m. Kouri et al. (1995) found that lifters who had never used steroids topped out around 25. It is a screen, not a verdict: genetics, measurement error and bad body-fat estimates all move the number.

How fast can someone build muscle naturally?

The Aragon and McDonald gain-rate models put it at roughly 0.7 to 1 kg a month in the first year of serious lifting, about half that in year two, and 1 to 2 kg a year for an experienced lifter. Rate of gain often says more than any single FFMI snapshot.

Does a normal testosterone test prove someone is natural?

No. A single total-testosterone number only shows someone is inside the normal range, and replacement therapy sits inside that range by design. A standard panel does not screen for synthetic steroids at all. A test that could support a natural claim needs the pituitary signals LH and FSH, which outside hormones shut down, plus a urine screen for the drugs themselves.

Can you tell someone is on steroids from their traps and shoulders?

No. Shoulders and traps do carry more androgen receptors, so the pattern is real in some users, but plenty of naturals are built that way and plenty of users are not. It is a hint at best, never a verdict.

How we judge

Records beat math

If someone admitted use, failed a test, or shows up in a court record, we say so and cite it. That's the only path to a Confirmed verdict.

When there's no record, we do the math

FFMI (fat-free mass index) is fat-free mass in kilograms divided by height in meters squared, then normalized to 1.80 m. A 1995 study of steroid users and non-users (Kouri, Pope, Katz, Oliva: Fat-free mass index in users and nonusers of anabolic-androgenic steroids) found the non-users topped out around 25. That's the ceiling we cite. Every FFMI number on this site is the normalized one; pages just say "FFMI". It is a screen, not a verdict: genetics, measurement error, and bad body-fat estimates all move the number.

Rate of gain often says more than any snapshot. When a page cites natural muscle-gain ceilings — roughly 0.7–1 kg a month in the first year of serious lifting, about half that in year two, and 1–2 kg a year for an experienced lifter — those figures come from the Aragon and McDonald gain-rate models ( What's My Genetic Muscular Potential? — Lyle McDonald, which lays out both). Pages cite this once here, not per article.

We also weigh:

How fast the physique changed, and at what age.
Training age — when they started lifting heavy.
How the body-fat estimate holds up across photos and roles.
What they've said on the record, and how they said it.

Arguments we don't make

Most natty-or-not arguments online are bad ones. These are the ones we refuse to use, and the reasons why.

"You can tell from the traps and shoulders." You can't. Shoulders and traps do carry more androgen receptors, so the pattern is real in some users, but plenty of naturals are built that way and plenty of users aren't. It's a hint at best, never a verdict.
"Nobody can be big and lean at the same time." People can. Being lean makes anyone look far bigger than the scale says, and a good six-pack fools most viewers into calling a normal-sized man huge.
"No gyno, no acne, no hair loss, so he's natural." These side effects depend heavily on genetics and dose. Many users never get any of them, and a 20-year-old can lose a lot of hair before anyone notices. Their absence proves nothing.
"His testosterone test came back normal." A single total-testosterone number only shows someone is inside the normal range. Replacement therapy sits inside that range by design, and a standard panel doesn't screen for synthetic steroids at all. A test that could actually support a natural claim needs the pituitary signals (LH and FSH), which get shut down by outside hormones, plus a urine screen for the drugs themselves.
"Someone else natural is that big." What another person can do has no bearing on what this person did.
Judging from one photo. Lighting, pump, tan, oil, camera angle, dehydration and editing can manufacture a physique. Film shots are the worst of all: those scenes are planned, and the actor is pumped and oiled for them. We prefer candid and behind-the-scenes images.
Treating steroids as magic. They are a large advantage, not a shortcut around food, training and genetics. People routinely overestimate what they do.

One more thing we try to hold onto: regaining muscle you already had is far easier and faster than building it the first time. A transformation that only gets someone back to a physique they'd already reached proves much less than it looks like it does.

The verdicts

Confirmed	Admission, failed test, or official record. Cited on the page.
Likely enhanced	The numbers or timeline sit well past what the evidence says nature allows.
Uncertain	Plausible either way. We show the math and let you decide.
Likely natty	Numbers, timeline, and history all fit a natural athlete.

Disclaimer

Every verdict except “Confirmed” is opinion and analysis of public information, not a statement of fact. Stats marked “estimated” are our best read of reported figures and photos. Quotes are verbatim and linked to their source. Photos are credited and licensed. If we got something wrong, tell us and we'll fix it.