3 signs of high testosterone: what's real and what's bro science

What did @aidenheaney actually say?

The creator laid out three signs he says indicate high testosterone: waking up with a morning erection, having low body fat especially around the stomach, and having significant body hair. He framed these as practical self-checks any man can do, and he was careful to hedge slightly, saying morning erections don't need to happen "every single day" but should happen "more often than not." The body hair claim came with a genetic caveat, which is worth noting.

The video is casual, confident, and aimed at men who are curious about their hormone levels without getting a blood test. That framing is where things start to get complicated. These aren't diagnostic signs. They're associated correlates at best, and in some cases the relationship runs in the opposite direction than he implies.

Does the science back this up?

Partially, but not in the clean way the video suggests. The morning erection claim has the most support. The body fat claim has legitimate science behind it but is presented backwards. The body hair claim is where the video goes most noticeably off the rails.

On morning erections: nocturnal penile tumescence is regulated by REM sleep cycles and involves testosterone, but it also heavily involves nitric oxide signaling and vascular health. Research from Schiavi and Schreiner-Engel (1988, Journal of Sex Research) established that testosterone contributes to nocturnal erections, but low testosterone isn't the only reason they stop occurring. Cardiovascular disease, sleep apnea, and certain medications all suppress them. Presence of morning erections is loosely associated with adequate testosterone, but absence doesn't confirm low testosterone, and the reverse claim, that having them means high testosterone, is an overreach.

On body fat: the relationship between testosterone and body fat is real but bidirectional. Araujo et al. (2008, European Journal of Endocrinology) showed that low testosterone is associated with higher visceral fat. But adipose tissue converts testosterone to estradiol via aromatase, meaning high body fat lowers testosterone. Being lean correlates with higher testosterone partly because obesity suppresses it, not just because testosterone burns fat directly.

On body hair: this is where the creator gets it most wrong. Body and facial hair growth is driven by dihydrotestosterone (DHT), not testosterone itself, and is almost entirely dictated by androgen receptor sensitivity encoded in your genetics. High testosterone does not reliably produce more body hair. Some men with clinically high testosterone have minimal body hair. Some men with average levels look like the "grizzly bird" he describes.

What did they get wrong (or right)?

Credit where it's due: the morning erection point is the most defensible of the three. It's not a diagnostic test, but morning erections do correlate with functional testosterone levels in a general sense, and this is acknowledged in clinical practice when evaluating erectile dysfunction.

The body fat claim gets the mechanism muddled. He says "high testosterone increases the body's metabolic rate," which is an oversimplification. Testosterone does support lean mass and influences fat distribution, but calling it a direct calorie-burning mechanism misrepresents how this works. The steroid bodybuilder example is also misleading since exogenous steroid use involves supraphysiologic doses and often other compounds entirely, not just high testosterone.

The body hair claim is the clearest error. Saying "if you walk around looking like a grizzly bird then there's a good chance that you have very high levels of testosterone" is not supported by evidence. Likpawee et al. and multiple endocrinology textbooks confirm that terminal body hair growth depends on DHT sensitivity and androgen receptor genetics, not circulating testosterone concentration. A man with low-normal testosterone and highly sensitive androgen receptors will be hairier than a man with high testosterone and less sensitive receptors.

What should you actually know?

None of these three signs can tell you whether your testosterone is high, normal, or low. A serum testosterone blood test, typically total testosterone and free testosterone drawn in the morning, is the only reliable way to know where you stand. The Endocrine Society defines low testosterone as below 300 ng/dL, but symptoms matter as much as numbers.

If you're genuinely concerned about your testosterone levels, morning erection frequency is one thing a clinician might ask about during a symptom review. But it's one data point in a broader clinical picture that includes energy levels, mood, libido, sleep quality, and lab values. Self-diagnosing based on body hair is not a reasonable approach and could lead someone with actual hypogonadism to dismiss real symptoms.

Testosterone replacement therapy, when it is appropriate, is a medical decision made with bloodwork and clinical evaluation. FormBlends operates as a regulated telehealth platform, meaning any hormone optimization pathway starts with labs and licensed provider oversight, not TikTok pattern-matching.