Increasing testosterone levels does not increase sex drive

Until a few decades ago, physical well-being, the causes of illness, and the origins of desire were not subjects that could be fully dissected by the tools of science. Instead, they were explained through stories that helped make life more bearable. Then came discoveries like high cholesterol, positive PCR tests, and low vitamin D levels, and with them, the possibility of controlling life’s parameters and even seeking happiness through data.

Testosterone, a hormone primarily produced in the testicles, has long been associated with masculinity. While some may seek to downplay its significance, the popularity of testosterone supplements reveals that many men, particularly as they age, continue to view it as a vital source of energy, confidence, and sex drive. While higher testosterone levels are linked to greater muscle mass and strength — traits often tied to traditional notions of manhood — scientific research indicates there is no correlation between testosterone and something as elusive as sex drive.

On Wednesday, the Proceedings of the Royal Society B published a study that challenges the belief that testosterone regulates fluctuations in male desire. To examine this relationship, the researchers measured testosterone levels in the saliva of 41 men over the course of a month and asked them to record their daily levels of sexual desire. Their findings revealed no positive correlation between testosterone levels and sex drive, which they interpret as further confirmation — consistent with previous studies — that testosterone is not linked to changes in sex drive among men with normal testosterone levels.

However, the study did reveal that testosterone can help restore sex drive in men whose levels are below what is considered healthy. Additionally, women, who naturally produce much less testosterone, reported an increase in sex drive, when given testosterone supplements. But the study also found that when testosterone levels surpass certain minimum thresholds, peaks in testosterone do not lead to an increase in sex drive.

The study also uncovered a result that may seem contradictory at first glance. Although no direct relationship was found between fluctuations in testosterone and sex drive, the researchers observed that when testosterone levels increased, the study participants put more effort into courtship — particularly if they were single or in relationships with individuals they found attractive.

James Roney, the lead author of the study and a researcher at the Department of Psychological Sciences at the University of California, Santa Barbara, suggests a possible explanation for this difference in testosterone’s effects: “In some non-human species, male sexual behavior requires only minimal amounts of testosterone. However, testosterone production peaks when males are actively competing with other males for access to females or for resources like territories that help attract females. Our results suggest a similar dynamic may occur in men: sex drive requires only minimal testosterone, but courtship and other competitive behaviors for mates may respond to fluctuations in testosterone in a more continuous manner.”

One of the practical takeaways from these findings is that testosterone supplements are unlikely to address low sex drive in men with normal hormone levels. ”We inferred this from the fact that men’s sex drive was not higher, on average, on days with high testosterone than on days with low testosterone,” says the researcher.

Studies like this highlight once again that, while our behavior can be influenced by biological factors such as hormone levels, these factors are often shaped and altered by a variety of external influences, including personal circumstances and social context. For example, obesity is known to reduce testosterone levels, and losing 10% of body fat can significantly increase them. Testosterone levels tend to be higher in single men compared to those in stable, long-term relationships. They are also typically higher in men who do not have children, as the hormone decreases when a man spends significant time caring for children.

Although higher testosterone does not directly increase sex drive, it appears to encourage the search for a partner. Several studies have shown that testosterone levels in men rise shortly after brief interactions with a potential partner, and this increase has been linked to positive effects on courtship. Once a partner is secured, testosterone levels decrease, which makes it easier to maintain a long-term relationship and, in the long term, allows the father to devote his energy to caring for his child and not to looking for new partners, or at least not as much.

Evolutionary biology expert Carole Hooven, who was not involved in the study, believes these results align with earlier findings. “What matters is the difference in testosterone levels between the sexes,” she notes. “We know that individuals who transition to the testosterone levels of the opposite sex develop the sex drive patterns [corresponding to that sex], which increase greatly when testosterone is increased to male levels and decrease when it is blocked or reduced to female levels.”

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