Morning erections are the gold standard for gauging testosterone, according to several male-oriented forums on Reddit, where an entire subcategory is devoted to the hormone, which is referred to online simply as T. In those groups—some aligned with the manosphere and others not—members swap and compare blood tests every six months. Being labeled in that universe as low T (low in testosterone) is a stigma that taps into several male anxieties: weak sexual drive, low energy, a certain timorous attitude toward life and a precarious bank balance.
Until about a decade ago, men lived largely oblivious to their hormones, but they have recently discovered that their wellbeing and reputation also depend, as with women, on chemical messengers that rise and fall erratically and therefore must be monitored and, when necessary, replaced with synthetic versions. Puberty is when testosterone concentrations in male blood are highest, between 500 and 700 ng/dl. From age 35 a slow but inexorable decline begins; it does not fall abruptly as estrogen does in women, but the steady drip of about 1% a year continues until levels reach those of an elderly man—around 300 ng/dl. That would be the physiological, natural decline.
But now that testosterone has been elevated to pop-culture status, nature must of course be corrected, and those natural declines are scrutinized in another rapidly expanding medical field: longevity. It was Robert F. Kennedy Jr., in charge of the MAHA (Make America Healthy Again) project, who revealed Donald Trump’s T figures on a podcast. He explained that, after reviewing his records, doctors had found “exceptionally high” testosterone levels for a man in his seventies. “He has the constitution of a god,” he reported. Kennedy Jr. said the secret of his energy, acuity and vigor lay in his hormones—specifically one of them. U.S. political analysts say Trump won the young male vote because he presented himself as the only candidate with enough testosterone to tackle the masculinity crisis that, in his view, the woke movement had created.
The day before the 2024 election, J. D. Vance was a guest on Joe Rogan’s podcast: “Have you seen all the studies linking testosterone levels in young men to conservative politics?” It was a rhetorical question; Vance himself supplied the answer: “It seems that less healthy people turn left.” Perhaps we are dealing with the only hormone that has always had an ideology. It was isolated and first synthesized in a laboratory in 1935 and quickly found a market eager to “correct deficits of masculinity.” Newsweek reported it was useful to “avoid feminine characteristics in men,” and Time magazine said a substance was being synthesized that could “revitalize the old and cure homosexuals.”
That was the first testosterone fever, which lasted until 1941, when a study found that supplementation with the hormone could cause prostate cancer. The impact was so strong it lasted for the rest of the 20th century. In 2010 several clinical trials linked TRT (testosterone replacement therapy) with the risk of strokes and heart attacks. The FDA recommended a comprehensive study of its real risks. That clinical trial, which included 5,200 men aged 45 to 80, ended in 2023 and concluded that testosterone was safe. By 2025 nearly 12 million people had obtained prescriptions for it, compared with scarcely one million who had been medicated in 2000, according to the consultancy IQVIA. Many others obtained hormones in gyms or online, where TRT is marketed as a lifestyle product.
Dr. Álvaro Campillo, of the longevity unit at The Beauty Concept, says it is relatively easy to identify a genuine testosterone deficiency. “They’re tired, they sleep worse even if they go to bed early, they’ve gained weight and lost muscle mass… In those cases, after the appropriate tests, replacement therapy is useful because it rebalances everything,” Campillo explains, adding that testosterone falls not only with age but also because of a sedentary lifestyle, poor diet, tobacco, alcohol or drug use and the accumulation of visceral fat, which feminizes men. Global figures from large studies, the most recent published in 2025, show that younger generations have lower testosterone levels than their predecessors at the same age—a circumstance Kennedy Jr. calls “an existential threat.”
“I would say testosterone’s role has been greatly simplified. It is not true that more testosterone automatically means more libido, more muscle or more masculinity, nor a stronger jawline. It does influence sexual desire, energy, muscle mass and body composition, but always within a broader context that also includes sleep, stress, vascular health, diet, exercise and other hormones,” explains Rafael Navas, a hormonal health expert at SHA Wellness. In his view, the goal should not be sky-high testosterone but the right level, and correcting a deficit if it exists and causes symptoms.
Some estimates put the prevalence of testosterone deficiency at 5.6% among men aged 30 to 79, mainly at older ages, but only one in five receives treatment. The paradox is that TRT use has surged especially among men 35 to 44. Physicians suspect many do not need it. The American Urological Association notes that one-third of men prescribed the drug do not have a diagnosis of hormone deficiency.
Although the impact of testosterone supplements in young men has been little studied, doctors believe in those cases testosterone would primarily increase muscle mass (many patients will already be pleased with that). But that is not what is reported on the Reddit forums, where men describe a before and after—a new life with more sex and a drive to take on the world. “They have probably also improved their diet and stopped drinking,” adds Dr. Navas, who thinks it is a mistake to reduce all male hormonal health to testosterone. “The body works like a symphony. Cortisol is directly related to the stress response, sleep, energy and metabolism. A man under chronic stress can present symptoms very similar to those of testosterone deficiency.”
What has also started to emerge in some clinics are young men with fertility problems and an almost zero sperm count. In almost all cases they had been taking prescribed testosterone obtained from online clinics and were never informed of that side effect. Apparently the supplements send the brain a message of excess and the testicles stop producing testosterone and sperm. According to The New York Times, the hormone is so effective at reducing sperm that it is being tested as a male contraceptive in a trial that entered its final phase in 2024. That, certainly, was not foreseen by Kennedy Jr. Nor by Pete Hegseth, the U.S. secretary of War, who likes to show off his deltoids and pectorals to his adversaries. He did so days before the Iran war in a video lifting weights cheered on by a court of toned torsos, and he repeated it in Guantánamo, where he stepped off a plane wearing shorts, took off his shirt and completed a set of bench presses before his troops. The video was posted on X under the name The High-T Department of War.
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