USA: Time-restricted fasting was shown to affect reproduction differently in male and female zebrafish in a recent study from the University of East Anglia. Importantly, some negative effects on eggs and sperm quality can be seen after the fish return to their normal food consumption.
According to the research, time-restricted fasting diets could cause fertility problems. The research team say that while the study was conducted in fish, their findings highlight the importance of considering not just the effect of fasting on weight and health, but also on fertility.
Prof Alexei Maklakov, from UEA’s School of Biological Sciences, said: “Time-restricted fasting is an eating pattern where people limit their food consumption to certain hours of the day. It’s a popular health and fitness trend and people are doing it to lose weight and improve their health.
“But the way organisms respond to food shortages can affect the quality of eggs and sperm, and such effects could potentially continue after the end of the fasting period.
“We wanted to learn more about how these sorts of diets can affect fertility in a popular model organism.”
The research team studied zebrafish (Danio rerio) to find out what happens when individuals are exposed to food during and after a period of fasting. They measured how males and females allocate resources to body maintenance versus production and maintenance of sperm and eggs, and the quality of the resulting offspring.
Dr Edward Ivimey-Cook, from UEA’s School of Biological Sciences, said: “What we found is that time-restricted fasting affects reproduction differently in males and females. Once the fish returned to their normal feeding schedule, females increased the number of offspring they produced at the cost of egg quality resulting in reduced offspring quality. The quality of male sperm also decreased.
“These findings underscore the importance of considering not just the effect of fasting on body maintenance but also on the production of eggs and sperm.
“Importantly, some negative effects on eggs and sperm quality can be seen after the animals returned to their normal food consumption levels following time-restricted fasting.
“More research is needed to understand how long it takes for sperm and egg quality to return to normal after the fasting period.”
View ORCID ProfileEdward R Ivimey-Cook, David S. Murray, Jean-Charles de Coriolis, Nathan Edden, Simone Immler, Alexei A. Maklakov doi: https://doi.org/10.1101/2022.07.18.500454.