A popular diet followed by many celebrities is linked to fertility problems

A study has found that intermittent fasting, a popular diet followed by many celebrities, such as Jennifer Aniston, Nicole Kidman and Cameron Diaz, can lead to fertility problems.

Intermittent fasting has gained wide popularity in recent years, with various studies revealing its benefits to public health, but some experts still question the effectiveness of this diet and its potential long-term health effects.

And a new study conducted on animals indicates that while fasting may be beneficial in losing weight, it may harm the chances of pregnancy.

The paper, published in Proceedings of the Royal Society B: Biological Sciences, says that following this diet can cause fertility problems.

Intermittent fasting is a diet that involves eating only during a specific period of time, and switching between fasting and eating according to a regular schedule, according to Johns Hopkins Medicine.

Researchers at the University of East Anglia in Norwich, England, tested how intermittent fasting affected the reproduction of zebrafish, measuring sperm and egg production as well as the quality of the offspring.

Zebrafish are commonly used in studies like these because they have all the major organs involved in metabolism, according to the University of Oxford.

Twelve male and 12 female fish were placed on a complete diet, while a different group of 18 male and 18 female fish were on an intermittent fasting diet. The fish in the fasting group were allowed to eat normally after 15 days.

30 males and 30 females were randomly paired on days 7, 15, 21, 28 and 35 of the study with fish of the opposite sex from the 'general population' in order to test reproductive performance.

The fish were given no more than five hours to breed, and if they failed, they were given another partner to repeat the process the next day.

On days 7, 15, 21 and 35 of the study, sperm were collected from each of the 30 male fish, and the eggs were evaluated after 2 and 24 hours.

The results showed that female fish in the intermittent fasting diet group had "significantly less" reproduction on days 7 and 15, on average, resulting in a lower number of offspring for females overall.

There were 163 offspring in the fully fed group compared to 75 in the fasting group.

Even after the females in the fasting group were fed normally again, there was still a drop in offspring, and the former had increased fin growth.

Scientists discovered that the quality of both the egg and sperm was negatively affected after returning to normal eating levels.

Professor Alexei Maklakov, an expert in developmental biology and author of the study, said: "The way organisms respond to food deficiency can affect the quality of eggs and sperm, and it is likely that these effects will persist after the end of the fasting period."

They suggested that these findings could be the result of women's bodies prioritizing their health and recovery from fasting over reproduction.

The fasted male fish also experienced an increasing decrease in sperm velocity over time and a "significant decrease in sperm quality".

However, the study authors note that the results "cannot be directly compared to a two-week period in mammals" due to metabolic differences.

Experts hope the research will encourage people to understand the importance of fasting's impact on fertility, not just weight loss.

Study author Dr. Edward Evemi Kok, an expert in biological sciences, said: “These results underscore the importance of taking into account not only the impact of fasting on maintaining the body, but also on egg and sperm production. More importantly, some negative effects on oocytes and sperm quality It can be seen after the animals return to their normal levels of food consumption after a time-restricted fast."

The researchers pointed out the need for more research to understand how long it takes for sperm and egg quality to return to normal after fasting.

Meanwhile, a study conducted earlier this year found that intermittent fasting does not help with weight loss, as calorie counting remains the most effective way to shed unwanted fat.

The researchers also previously found that intermittent fasting did not actually lead to more weight loss in obese people than limiting daily calories.

Another study from November 2022 found that intermittent fasting and skipping breakfast were associated with an increased risk of dying from cardiovascular disease.