What did @onehottrail actually say?
The creator ran an informal group blood test and found that Spencer, the leanest guy in the group, had 34% higher total testosterone than the biggest person and nearly double the creator's own level. Their explanation: total testosterone is a misleading metric because free testosterone is what actually drives anabolic effects. They also flagged that pre-draw habits, specifically sleep, caloric status, and recent training, can distort results significantly.
To illustrate the free testosterone point, they walked through a math example: if Spencer's SHBG is high enough that only 1% of his total testosterone is free, his free T comes out at 9.28 ng/dL. If another person has 2% free, their free T is 13.44 ng/dL, which the creator calls "45% higher and much more anabolic." They close by acknowledging the whole experiment has "a lot of confounding variables."
Does the science back this up?
Yes, mostly. The distinction between total and free testosterone is well-established and clinically meaningful. The claim that free testosterone is the more relevant androgenic signal is supported by decades of endocrinology research, though "more anabolic" is a slight oversimplification.
SHBG binds testosterone tightly and renders it biologically inactive for most tissues. Free testosterone, plus loosely albumin-bound testosterone, makes up what researchers call bioavailable testosterone. Vermeulen et al. (1999, Journal of Clinical Endocrinology and Metabolism) demonstrated that calculated free testosterone correlates more closely with clinical androgen status than total testosterone in men with abnormal SHBG. Bhasin et al. (2018, JCEM) reinforced this in their testosterone threshold research, noting that SHBG variability complicates total T as a standalone diagnostic marker.
On the pre-draw habits point, the science is also solid. Hackney et al. (2012, Current Sports Medicine Reports) confirmed that prolonged intensive exercise can suppress testosterone transiently, particularly under conditions of caloric deficit or sleep loss. The creator is right that a hard training session the day before a blood draw can skew results.
What did they get wrong (or right)?
They got the core biology right. Calling free testosterone the metric that "really matters" is a defensible clinical position, and the SHBG explanation is accurate enough for a social media audience.
Where things get slightly sloppy is the phrase "much more anabolic, assuming all else was equal." Free testosterone availability does influence androgenic and anabolic signaling, but anabolism also depends on androgen receptor density, intracellular testosterone metabolism via 5-alpha reductase and aromatase activity, and downstream signaling. Saying free T directly equals anabolic outcome is cleaner than the actual physiology warrants. Kraemer and Ratamess (2005, Sports Medicine) noted that the anabolic response to circulating testosterone is modulated by receptor sensitivity, not just circulating levels.
The numerical example is also a teaching tool, not a real clinical scenario. A free testosterone fraction of 1% to 2% is within the plausible range, but presenting it as a concrete illustration without noting that labs typically measure free T directly or via validated calculation could mislead viewers into thinking they need to do their own math. They should not.
What should you actually know?
If you are evaluating your own testosterone status, total testosterone alone is not enough. A complete picture requires total testosterone, SHBG, albumin, and calculated or directly measured free testosterone. Many telehealth panels and primary care workups stop at total T, which can miss both functional hypogonadism in men with high SHBG and unnecessary concern in men with low total T but normal free T levels.
The Endocrine Society's 2018 clinical practice guidelines (Bhasin et al., JCEM) recommend measuring total testosterone first thing in the morning on two separate occasions, precisely because of the diurnal variation and day-to-day fluctuation the creator gestures at. Pre-draw standardization, consistent sleep, no intense exercise 24 to 48 hours prior, and morning timing, matters more than most patients are told.
One thing this video does not address is that SHBG itself is modifiable. Obesity, insulin resistance, thyroid dysfunction, and liver disease all affect SHBG independently of testosterone production. A man with low free T might benefit more from addressing metabolic health than from testosterone therapy. That clinical layer is missing here, though the creator never claimed to cover it.