More Testosterone Won’t Make a Better Soldier or a Tougher Man—Aggression and Strength Drive T Levels, Not the Other Way Around

Defense Secretary Pete Hegseth has mandated annual testosterone testing for U.S. service members aged 30 and above. However, the military lifestyle itself may be contributing to lower T levels. When the Secretary announced this in July 2026, he did not specify what level of testosterone would be deemed "low" enough to warrant treatment. This omission is significant, as the definition of "low" depends on the lab performing the test and the guidelines followed by the doctor.

The surge in testosterone prescriptions has coincided with a national craze, with nearly 12 million prescriptions written in 2025, a 154% increase since 2020. The majority of these prescriptions have been issued to men in their late 30s and 40s through online clinics promoting testosterone as a lifestyle enhancement.

While testosterone is often perceived as a "male" hormone, people of all genders produce it in varying amounts. In cisgender boys and men, testosterone levels rise during puberty, leading to muscle growth, body hair development, and sperm production. However, these levels naturally decrease in adulthood, typically beginning around age 30.

Healthy men typically have testosterone levels between 300 to 1,000 nanograms per deciliter. Within this range, an individual's testosterone level does not necessarily correlate with the "masculine" traits that some associate with it.

Testosterone levels fluctuate throughout the day and season, making it essential for doctors to test when symptoms arise. Regular screening of healthy men could potentially be harmful, as testosterone therapy can lead to serious side effects. For instance, it can suppress the body's natural production of testosterone, leading to smaller testicles and reduced sperm production. Moreover, testosterone can stimulate oil glands and hair follicles, resulting in acne, hair loss, and in some cases, breast tissue growth.

Research has shown that the correlation between testosterone levels and aggression is minimal. A 2001 analysis of data from 45 studies involving nearly 10,000 people found only a small association between testosterone levels and aggression. When researchers conducted experiments to study whether administering testosterone to participants increased aggression, they found only weak evidence.

In fact, they discovered that testosterone's effects on aggression primarily appeared in men who were already dominant or impulsive. The data suggests that the relationship between aggression and testosterone runs in the opposite direction—behavior influences testosterone levels.

In addition to social factors, there is evidence that testosterone levels can be affected by experiences of physical care. A study found that men who spent extended periods handling a gun experienced larger testosterone spikes and displayed more aggressive behavior than those who touched a board game. Similarly, new fathers experienced a more significant decrease in testosterone levels when they engaged in physically demanding care for their children.

Aggression is often triggered by threats to a man's sense of masculinity rather than biological factors. A study of more than 200 adolescent boys and their parents found that boys who reacted aggressively to threats to their masculinity were mainly those who experienced external pressure to conform to masculine ideals. This pressure was strongest among boys whose parents endorsed specific beliefs about manhood, such as the notion that men should hold power over others.

Research indicates that biology, social pressure, and development collectively determine how a boy grows into a man. While hormones may serve as a catalyst, the social environment ultimately shapes the outcome. The grueling nature of military service can contribute to lower testosterone levels. A 2020 study of U.S. Army Rangers found that the sleep deprivation inherent in training significantly reduced testosterone levels.

Chronic stress, sleep deprivation, blast exposure, and poor nutrition can collectively result in "Operator Syndrome," a cluster of health issues that can push a 35-year-old's testosterone levels closer to those of a man in his 80s.

Ironically, the military imposes the very conditions that suppress testosterone and then suggests treating the resulting symptoms with more testosterone. Handing troops testosterone to rectify these issues does not address the underlying causes, which include sleep deprivation, stress, and injury. In February 2025, the Pentagon halted gender-affirming hormone therapy for transgender troops, arguing that such care is incompatible with the force's "readiness" and "lethality."

However, prescribing testosterone to align a cisgender man's body with the Pentagon's masculine ideals is hormone therapy, too. Legal advocates are challenging this decision.