09:18
creatine
A brand-new randomized controlled study appears to show that creatine's lean-mass gains are just water weight, not real muscle — but Physionic argues that conclusion overreaches: the study exposes a real design flaw in prior creatine research (failing to control for initial water retention), yet its own muscle-biopsy data, plus outside research on contractile proteins, still show creatine has a genuine muscle-promoting effect.
A new randomized controlled study had participants take creatine or placebo for 13 weeks, but uniquely measured lean body mass at baseline, again after a 1-week 'wash-in' period (before any resistance training), and again at 13 weeks, then ran everyone through the same 12-week training program.
Creatine alone (no training) produced a statistically significant lean-body-mass increase within the first week — too large and too fast to be real muscle, indicating it's water retention picked up by DEXA lean-body-mass measurement.
When the study compares baseline directly to 13 weeks, creatine shows a lean-mass advantage over control; but when the inflated 1-week 'wash-in' measurement is used as the new baseline instead, creatine's advantage disappears — this is the finding media headlines seized on.
Physionic's first rebuttal: lean body mass and fat-free mass are imprecise proxies for muscle, since they also include cartilage, bone, and other non-fat tissues, so an absence of a detectable LBM/FFM effect doesn't necessarily mean an absence of a muscle effect.
The same study also took muscle biopsies and directly measured the cross-sectional size of individual muscle fiber types (1, 2A, 2AB, 2B), and found significant increases in muscle cell size with creatine.
Second caveat Physionic raises: increased muscle cell size doesn't by itself prove increased contractile tissue (functional proteins), since it could still reflect water pulled into the cell rather than growth of muscle-building machinery.
Physionic cites separate studies that directly measure myofibrillar/contractile proteins like myosin, which still show a creatine advantage — extending the evidence beyond this one study's proxies.
Reasons offered for why the main study didn't detect a lean-mass or fat-free-mass effect: LBM is an imprecise gain marker; detecting a small effect from a single molecule typically requires more precise testing, a longer study duration, or a larger sample specifically powered for that smaller effect — and this study's sample size was sufficient to detect LBM differences but not necessarily finer muscle-specific differences.
Overall conclusion: the study is 'still an important study' because it illuminates a real deficiency in prior creatine research, but it does not, in Physionic's view, overturn creatine's effectiveness for muscle growth given the other lines of evidence — creatine remains 'still a fantastic supplement' for those taking it for muscle.
Physionic promotes a paid 'Physiologic Insiders' extended version of the video covering further nuances on creatine and muscle, plus live sessions and additional study-review content.
The methodological fix this study introduces — a 1-week 'wash-in' remeasurement before training starts — is presented as the specific technique that lets researchers separate real training-driven muscle gain from initial creatine-driven water retention, a step prior studies skipped.
Physionic's rebuttal structure is layered: he first shows the same study's own biopsy data (a more precise measure than LBM/FFM) still favors creatine, then reaches for external studies on contractile proteins to address the remaining objection that biopsy-measured cell size could itself just be water.
He draws a distinction between statistical power to detect a coarse outcome (lean body mass difference) versus power to detect a finer, more specific outcome (actual muscle growth) — the study may have enough participants for the former but not the latter, which is easy to miss when only reading the headline result.
A viewer comment flags a specific technical distinction the video may blur: fat-free mass (FFM) includes bone mass while lean body mass (LBM) typically doesn't, and since resistance training can itself increase bone mass, using FFM (as the study at 5:26 does) could introduce a further confound moving the measure even further from true 'muscle' than LBM would.
A top-liked audience comment adds context beyond the transcript's own claims: one of the study's researchers has a sponsorship relationship with a creatine-producing company yet still published findings skeptical of creatine's lean-mass effect, offered by that commenter as a caution against assuming funding source predicts study conclusions.
«All previous creatine research has a fatal flaw, according to a brand new study.»
— 00:00
«The reason this is important is to measure 1 week later again is because the creatine leads to water retention, which gets picked up in lean body mass measures like those used in many studies.»
— 01:25
«Notice how creatine no longer offers an advantage.»
— 02:58
«Plainly, it tells us that lean mass increases are only water weight, not an actual lean mass increase from the training effect on creatine.»
— 03:08
«I wouldn't want to be someone who's been saying that creatine is effective for muscle and performance right now.»
— 03:37
«clearly, we see significant increases in muscle cell size»
— 06:03
«across multiple lines of evidence, we still see creatine have a muscle-promoting effect.»
— 07:21
«However, it does not inform on the effectiveness of creatine for muscle growth in as commanding a way as has been portrayed by many.»
— 08:28
«there's still many lines of evidence, better evidence, that indicate that creatine still promotes muscle growth. So, if you're taking it for that outcome, creatine is still a fantastic supplement.»
— 08:40
Reception
Audience appreciates the scientific rigor and content quality, though many respectfully challenge the study methodology and maintain that creatine benefits them in practice.
Physionic's counter-argument is methodologically careful within its own terms: it correctly isolates the water-retention confound the new study identifies, then answers the 'so creatine doesn't build muscle' overreach using the same study's biopsy data plus outside evidence on contractile proteins, so the video reads as a targeted correction of a media narrative rather than a rebuttal of the study's actual finding.
09:18