Could skipping dinner get your love life back on track?
A new international study found that a particular form of intermittent fasting boosted the libido of male mice, raising questions about whether it could trigger a similar effect in humans.
“A lack of sexual desire is not necessarily perceived as problematic — but some people suffer from it,” said Dr. Dan Ehninger, lead author of the study produced by the German Center for Neurodegenerative Diseases. “Fasting could potentially serve as a useful addition to existing treatment options.”
Low sex drive is more common than you might think, affecting up to one in five men and an even larger number of women at some point in their lives, according to the Cleveland Clinic.
For some, this dips into hypoactive sexual desire disorder (HSDD). People affected by the condition experience a persistent lack of motivation or desire to have sex for no clear reason, which leads to significant distress in their personal lives.
Experts say diagnosing and treating HSDD is challenging, mainly because the science behind sexual desire is still not fully understood. However, there are medications available, and some people find that therapy and lifestyle changes can help.
How intermittent fasting boosted mice’s mating game
In the study, researchers set out to explore how fasting affects the offspring of male mice, but they stumbled upon an unexpected twist: senior male mice reproduced at a surprisingly high rate after being put on a long-term restricted diet.
“It was a bit of detective work to uncover the real cause,” Ehninger said. “Eventually, we realized: it is a matter of behavior. The fasting males had significantly more sexual contacts than mice that could eat freely.”
Ehninger noted that this increase in mating behavior more than compensated for the age-related physiological limitations of the fasting seniors, such as lower testosterone levels and reduced sperm quality.
In the study, male mice were put on an intermittent fasting regimen starting at just two months old. For 24 hours, they could eat all they wanted, but for the next 24 hours, it was strictly water.
The males followed the diet for 22 months. When they were finally introduced to females, it was clear that they were more than ready to mingle.
Those that fasted for at least six months were significantly more sexually active than the freely eating control group. Interestingly, younger mice who followed the fasting diet for just six months also showed an increase in mating behavior.
However, a group that fasted for only a few weeks didn’t show the same spike in libido.
“For intermittent fasting to increase sex drive, it takes some time,” said Dr. Yu Zhou, a professor at Qingdao University who collaborated on the study. “Based on our experiments, the minimum duration appears to be somewhere between six weeks and six months.”
The serotonin connection
Researchers believe the surge in libido traces back to serotonin, a neurotransmitter known to influence sexual behavior.
In humans, high levels of serotonin are typically linked to a decreased sex drive, while lower levels are often associated with a boost in libido.
Serotonin production depends largely on tryptophan, an essential amino acid that the body can’t produce on its own, meaning we need to get it through our diet.
As a result, the fasting regimen in mice caused a deficiency in tryptophan, which lowered serotonin levels — and, in theory, boosted their sex drive.
“In view of this, I consider it very plausible that sexual desire in humans can be influenced by fasting — possibly not only in men, but also in women, since serotonin affects their libido as well,” Ehninger said.
Researchers are unsure whether the drop in serotonin levels is tied to the specific eating regimen followed by the mice or if it would also occur with other types of fasting.
Ehninger said further studies are also needed to clarify whether the effect could happen with general caloric restriction, where food is continuously available but in smaller amounts.
