This experimental study, conducted by a team of biologists from the University of East Anglia on an animal model, reveals a link between one type of intermittent fasting, restricted fasting, and an increased risk of fertility disorders.
These findings, published in the Proceedings of the Royal Society B: Biological Sciences, draw attention to the lesser-known effects of intermittent fasting on reproduction.
The research conducted on zebrafish shows that intermittent fasting affects reproduction differently in males and females. Moreover, some of the negative effects on egg and sperm quality can still be observed long after the animals have returned to their “normal” eating habits. The question, of course, is whether these results can be generalized to humans, but the research team says that although the study was conducted on fish, the impact of fasting on humans should be considered in terms of weight and health, but also fertility.
Lead author Maklakov, a biology professor at UEA, commented on the results, Time-restricted fasting involves restricting food intake to a certain period of time during the day. This diet is becoming increasingly popular and many studies have documented some benefits for metabolic health and weight maintenance.
The “negative” effects of intermittent fasting are less well documented: however, the way organisms react to food deprivation can affect egg and sperm quality, and these effects seem to persist long after the fasting period is over.
In the study the UK team wanted to find out more about how these types of diets might affect fertility, and are working on a common model, the zebrafish (Danio rerio), to find out what happens when these models are exposed to food during and after a period of fasting. In particular, the team assesses how males and females allocate resources for overall body function in relation to the production and maintenance of sperm and eggs and the quality of the resulting offspring. This work reveals that :
- Time-restricted fasting affects reproduction differently in males and females.
- When animals return to normal feeding habits, females increase the number of offspring, but at the expense of egg quality, which is reduced.
- Sperm quality is also reduced.
Fasting has detrimental effects on egg and sperm production, and these effects can be long-lasting: According to the research team”It is important to note that some of the negative effects on egg and sperm quality can be observed after the animals have returned to their normal diet.”
The team plans to investigate potential interventions to mitigate the negative effects of intermittent fasting on reproduction and monitor the long-term effects to determine whether they are reversible and how long it takes for the reproductive function to return to normal.
