Mark McGwire: natty or not?
Confirmed 70 home runs in 1998, the record that saved baseball and then unravelled
Short answer. Verdict: confirmed. At the peak physique on this page, Mark McGwire is 6'5" (196 cm) and 245 lbs (111 kg) at roughly 15% body fat. That works out to an FFMI of 23.6, against the ~25 mark cited as the natural ceiling.
The numbers (estimated)
| Peak physique | Listed playing weight, 245 lbs, through the late-1990s home run years |
|---|---|
| Height | 6'5" (196 cm) |
| Weight | 245 lbs (111 kg) |
| Body fat | ~15% |
| FFMI | 23.6 — ~25 is the cited natural ceiling |
Era by era (estimated)
| Era | Year | Age | Weight | Evidence | Body fat | FFMI |
|---|---|---|---|---|---|---|
| Record season, 70 home runs | 1998 | 35 | 245 lbs (111 kg) | reported | ~15% | 23.6 |
Note. Playing weight is the listed figure; the body-fat number is an estimate. The verdict below is not — it rests on his own admission. See the methodology page for how we judge.
Mark McGwire admitted it, on camera, with a date range attached. On January 11, 2010 he told Bob Costas: “I wish I had never touched steroids. It was foolish and it was a mistake. I truly apologize. Looking back, I wish I had never played during the steroid era.” He said he used on and off for about a decade, starting in the 1989-90 off-season, again after a 1993 injury, and through the 1990s — including 1998.
1998 is the year that matters. That season he hit 70 home runs and broke a record that had stood since 1961.
Confirmed.
The numbers, and why they are not the point
McGwire is listed at 6’5” (196 cm) and 245 lbs (111 kg). Run that through the FFMI math and the answer is unremarkable — a very big man of normal build reads as ordinary on an index that divides by height squared.
That is the useful lesson on this page. FFMI catches bodybuilders. It does not catch a tall athlete taking steroids for recovery and bat speed, which is what McGwire says he was doing. For an athlete like this, the evidence is the record, not the arithmetic. Here the record is his own confession.
The andro footnote
During the 1998 chase, reporters found androstenedione in his locker and he acknowledged taking it. It was legal in baseball at the time, banned by the NFL and the IOC, and not classified as an anabolic steroid under U.S. law until 2004. Andro was never the real story, and his 2010 statement is about the things that were.
Verdict
Confirmed — by admission, twelve years after the record and without a positive test forcing it. What he actually took, and in what amounts, he has never itemized.
In their words
“I wish I had never touched steroids. It was foolish and it was a mistake. I truly apologize. Looking back, I wish I had never played during the steroid era.”
Common questions
Is Mark McGwire natty or on steroids?
This site rates Mark McGwire as confirmed, the only verdict here stated as fact. It takes an admission, a failed test or an official record, and the one behind this page is cited in the sources below.
Has Mark McGwire ever failed a drug test or admitted to using PEDs?
The record that settles this page is listed in the sources below and described in the article above. It is what makes the verdict confirmed rather than an opinion.
What is Mark McGwire's FFMI?
About 23.6. That comes from 6'5" (196 cm) and 245 lbs (111 kg) at roughly 15% body fat, normalized to 1.8 m. Drug-free lifters in the Kouri 1995 study topped out near 25.