Study finds 54 percent drop in men’s testosterone levels since 1972
Friday 24th July 2026 on 12:45 in
Norway
A new study shows men’s testosterone levels have fallen by 54 percent from 1972 to 2019, based on data from over 118,000 men in Denmark, Finland, and the US, according to Danish newspaper B.T., citing The Guardian and Berlingske.
Professor Hagai Levine, one of the researchers behind the study, told The Guardian the decline represents a major crisis for male reproductive health.
Per Medbøe Thorsby, a hormone specialist and senior consultant at Oslo University Hospital’s Hormone Laboratory, said the findings are not surprising and likely linked to rising obesity.
“Obesity is probably the main factor. Losing five to ten percent of body weight can increase testosterone levels,” Thorsby told Dagbladet.
He added that declining fertility in both men and women over the same period is a more pressing concern, possibly tied to environmental toxins that mimic estrogen, such as those found in some plastics.
Thorsby cautioned that the study’s methodology may introduce uncertainty, as testosterone measurement techniques have changed significantly since the 1970s, making direct comparisons difficult. Claus Højbjerg Gravholt of Aarhus University raised similar concerns in Berlingske.
Oslo’s Hormone Laboratory has recently developed a new testosterone measurement method, which Thorsby said holds promise.
Norway lacks reliable data on whether its men have experienced a similar decline, but Thorsby suggested a dedicated Norwegian study may be warranted. He noted that about one percent of Norwegian men over 20 receive prescribed testosterone, a figure he believes may be too low.
“Around two percent of men over 40 have genuine testosterone deficiency and should receive treatment,” he said.
Thorsby warned against unnecessary testosterone use, citing risks to fertility, blood clotting, and heart health. He advised that only men with symptoms such as rapidly declining libido or lack of morning erections should consider testing, with two morning samples required before treatment is considered.