From the US Army to longevity clinics: Testosterone is back in fashion

US Secretary of Defense Pete Hegseth, who prefers to call himself the "Secretary of War," announced a new program about a month ago: every soldier in the US Army over the age of 30 will undergo a test to detect their testosterone levels. According to him, he wants soldiers to have "testosterone levels appropriate for peak performance," claiming that supplementation when necessary will allow for a "healthy and clearly dominant fighting force."

Hegseth is not the only one in the Donald Trump administration who has developed an interest in testosterone. Secretary of Health Robert F. Kennedy Jr. is also interested in easing access to the hormone and admitted that he himself takes it. The hormone is marketed today legally or illegally in gyms, "quality of life" clinics, and online, forming a market of about $2 billion. In Israel, too, unofficial and unregulated versions of the hormone can be obtained.

"I meet patients who simply bought it on the internet," says Dr. Liat Barzilai-Yosef, a specialist in internal medicine and endocrinology, and director of the obesity treatment clinic at the Meir Medical Center of the Clalit group. Professor Zvi Naor, an expert in biochemistry and molecular biology at Tel Aviv University, adds that "interest is seen mainly among wealthy men aged 60 and over."

Andropause: Reality or Myth?

The interest in testosterone corresponds to two cultural trends in the US that are spilling over into the world: an increased interest in affirming masculinity and the blurring of boundaries between medical products and quality-of-life or longevity products. The temptation is clear: if the hormone level drops with age, perhaps returning it to our younger days will also turn the body back. Reality, however, is more complex.

"Andropause, or male menopause, is a real phenomenon," says Barzilai-Yosef. "The decline in male hormones begins at age 30, but it is gradual until the end of life. A testosterone level below the norm is associated with a decrease in function and libido, energy, muscle mass, and abdominal obesity. We see a decrease in body hair, sometimes anemia, and sometimes a decrease in bone density to the point of osteoporosis."

Risks and Scientific Evidence

Do low levels require supplementation? Barzilai-Yosef explains: "It depends on the reason. The testicles secrete testosterone in response to a signal from the brain, so it is necessary to understand if the problem originates in the brain, for example due to a tumor or other medications, or if it originates in the testicle. If we have ruled out other causes, testosterone can be added in gel or injections."

The problem begins when men ask for testosterone even if its level is within the norm. Studies show that supplementation when levels are normal does not always translate into improved vitality or cognition. Furthermore, Professor Naor suggests that the effect on longevity might actually be in the opposite direction: "Men live fewer years than women, and there is a hypothesis that this is because of testosterone. A study on choir boys in Italy who underwent castration at the end of the 19th century showed that they lived longer than the male average."

Additionally, testosterone can accelerate cancerous processes in the prostate or cause thickening of airway tissues in those suffering from severe sleep apnea. Barzilai-Yosef warns that the damage can be significant, especially in young people: "If you supplement testosterone at a young age, the brain receives a signal that there is enough, and it stops independent production. This can lead to shrinkage of the testicles, a decrease in sperm production, and abnormal hematology. Unfortunately, these problems are not always reversible."