It's one of Hollywood's favorite diets, promoted by a legion of famous and fit fans, including Jennifer Aniston and Mark Wahlberg.
Now, scientists say intermittent fasting may help boost sexual desire – especially in older men.
Specifically, a group of German and Chinese researchers found that diet affected the concentration of serotonin – a hormone that can affect mood – in the brain.
Experiments with mice also showed that this phenomenon was most effective in those who had followed the diet for at least six weeks.
Experts, who described this discovery as important, warned that more research is needed to find out whether the decrease in serotonin that increases sexual desire would also occur with other types of fasting.
Dr. Dan Ehninger, head of the research group at the German Center for Neurodegenerative Diseases (DZNE) and lead author of the study, said:
"We realized it was a behavioral issue. The fasted mice had significantly more sexual encounters than the ad libitum fed mice."
"In other words, these animals had an unusually high mating frequency and, as a result, a high number of offspring for their age. Their sexual behavior more than adequately compensated for age-related physiological limitations."
"However, it is currently unclear whether the decrease in serotonin levels is related to our specific eating regimen or whether it would also occur with other types of fasting. Future studies will need to clarify this," he added.
Despite dozens of studies suggesting that intermittent fasting – which became popular in the early 2010s – is effective, experts remain divided about its effects and long-term impacts on health.
Some argue that those who fast typically consume a relatively large amount of food at one meal, resulting in them not actually reducing calories - a popular method for losing weight.
Some even warn that this diet can increase the risk of strokes, heart attacks, or premature death.
In the new study, a group of male mice underwent an intense form of intermittent fasting starting at two months of age. They were allowed to eat whatever they wanted for 24 hours, followed by 24 hours of water only.
The other group had no dietary restrictions. Both groups were kept together, without contact with female mice.
Then, they were introduced to three-month-old female mice that had not followed any dietary restrictions.
Scientists found that in sexually active male rats, serotonin was present at extremely low levels.
Serotonin relies on the amino acid tryptophan to be converted by the body.
But tryptophan can only be obtained through diet or released from the breakdown of the body's protein stores, such as muscle.
As a result, when tryptophan levels are low, less serotonin is produced.
"The lack of serotonin was clearly a result of fasting. These mice were, so to speak, sexually uninhibited, and normal self-control was reduced," said Dr. Ehninger.
Writing in the journal Cell Metabolism, the researchers also noted that a similar effect was observed in younger mice, which had begun fasting at two months of age, but had only followed the diet for six months before being introduced to females.
They were also more sexually active than mice of the same age who had no dietary restrictions.
However, this effect was not observed in other groups – both young and old – who had only fasted for a few weeks.
Professor Yu Zhou, a neurobiology expert at Qingdao University, added:
"To increase sexual desire through intermittent fasting, a certain period of time is needed.
Based on our experiments, the minimum duration appears to be somewhere between six weeks and six months.”
"Given this, it seems very plausible to me that sexual desire in humans could be affected by fasting - perhaps not just in men, but also in women, as serotonin also affects their libido," he said. Dr. Ehninger reports GazetaExpress.
This research also comes amid concerns about a global sex crisis – or more accurately, the lack of sex.
A recent survey showed that more than a quarter (27%) of Britons are having less sex than before, while one in six admitted to having had no sexual contact at all during the entire year.
According to a Royal College of Occupational Therapists survey of 2,000 adults last year, men and women typically have sex 46 times a year – once every eight days.
But some have much less frequent sexual activity, with one in ten reporting having sex less than once a year.
Sex and intimacy are linked to several health benefits, including improved heart health, reduced stress, and even improved mental health. /Express newspaper/
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