What did @josezunigabrands actually say?
The creator told 190,000-plus viewers to look at their hands: "If your ring finger is shorter than your pointer finger, you're genetically predisposed to have lower testosterone level." He framed this as a legitimate self-diagnostic tool called the 2D:4D ratio, implied the result means you "probably have low testosterone," and then pivoted directly into promoting a supplement called Get Strong, available on TikTok Shop. He says he's been taking it for two months and called it "incredible." The hand test is presented as a gateway to the product pitch, which is worth keeping in mind when evaluating the whole video.
To be fair, he did tell viewers not to "freak out" and positioned supplementation as a natural optimization strategy rather than a medical intervention. That framing is more responsible than a lot of TRT content on the platform. But the core claim, that finger length ratio tells you whether you have low testosterone, is where things get shaky.
Does the science back this up?
Partially, but not in the way he implies. The 2D:4D ratio is a real concept in biology, but it measures prenatal androgen exposure, not your current testosterone levels. That distinction matters enormously, and he doesn't make it.
The research on 2D:4D goes back decades. Manning et al. (1998, Human Reproduction) established that lower 2D:4D ratios, meaning a longer ring finger relative to the index finger, are associated with higher prenatal testosterone exposure in males. Note the direction: a longer ring finger, not a shorter one, is the "high testosterone" pattern. The creator got this backwards. He said a ring finger shorter than the pointer finger predicts lower testosterone, which is actually the typical female pattern, and reflects fetal hormone environments from the first trimester, not adult circulating testosterone.
More critically, a 2024 meta-analysis by Geniole et al. (Hormones and Behavior) found that 2D:4D has weak and inconsistent associations with adult testosterone levels. Using it as a personal diagnostic tool is not supported by the literature. Endocrinologists use serum blood tests, not hand geometry, to assess hypogonadism.
What did they get wrong (or right)?
He got the ratio direction wrong. A shorter ring finger relative to the index finger is actually associated with higher prenatal estrogen exposure, not lower testosterone in adult life. The "low T" pattern in his framing is inverted from what the research describes.
He also conflated prenatal hormone exposure with current adult testosterone status. These are not the same thing. A man can have had high prenatal androgen exposure and still develop secondary hypogonadism in adulthood due to obesity, sleep apnea, stress, or other factors. The hand test tells you nothing about where your levels are today.
What he got right: the general advice to "max out your testosterone naturally" through lifestyle is sound. Sleep, resistance training, body composition, and stress management all have real evidence behind them for supporting healthy testosterone levels. He didn't tell anyone to inject anything or skip a doctor, which puts him ahead of a lot of creators in this category.
The supplement pitch is unverifiable. "Get Strong" is not an FDA-approved treatment for anything, and two months of personal use from a paid promoter is not clinical evidence.
What should you actually know?
If you're genuinely concerned about low testosterone, a finger length test will not help you. The only way to know your testosterone levels is through a blood test measuring total testosterone, free testosterone, SHBG, and LH, interpreted by a clinician who knows your full health picture.
Clinical hypogonadism is diagnosed when total testosterone falls below approximately 300 ng/dL alongside symptoms such as fatigue, reduced libido, loss of muscle mass, or mood changes. Symptoms alone are not diagnostic, and neither is your hand.
Lifestyle interventions do have real evidence. A 2011 study by Leproult and Van Cauter (JAMA) found that one week of sleep restriction to five hours per night reduced testosterone levels by 10-15% in young healthy men. Resistance training, achieving a healthy body weight, and reducing chronic stress are all interventions with meaningful evidence. These are worth pursuing regardless of what your ring finger looks like.
If a supplement company is selling you a product through a TikTok influencer who's pitching a finger test as the diagnostic, that's not a clinical pathway. Talk to a physician or a telehealth provider who can actually order labs before spending money on anything.