Time-restricted fasting diets could cause fertility problems according to new research from the University of East Anglia.
A new study published today shows that time-restricted fasting affects reproduction differently in male and female zebrafish.
Importantly, some of the negative effects on egg and sperm quality can be seen after the fish return to their normal levels of food consumption.
The research team says that while the study was conducted in fish, their findings highlight the importance of considering not only the effect of fasting on weight and health, but also fertility.
Professor Alexei Maklakov, from the UEA Faculty of Biological Sciences, said: “Time-restricted fasting is an eating pattern in which people limit their food intake to certain times of the day. It is a popular trend of health and fitness and people do it to lose weight and improve their health.
“But the way organisms respond to food shortages can affect egg and sperm quality, and such effects could continue after the end of the fasting period.
“We wanted to find out more about how these types of diets can affect fertility in a popular model organism.”
The research team studied the zebrafish (danio rerio) to find out what happens when people are exposed to food during and after a period of fasting. They measured how males and females allocate resources to body maintenance versus sperm and egg production and maintenance, 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, the females increased the number of pups they had.” produced at the cost of ovum quality, resulting in reduced quality of offspring. The quality of the male sperm also decreased.
“These findings underscore the importance of considering not only the effect of fasting on the maintenance of the body, but also on egg and sperm production.
“Importantly, some of the negative effects on egg and sperm quality can be seen after the animals returned to their normal levels of food consumption after a time-restricted fast.
“More research is needed to understand how long it takes for sperm and egg quality to return to normal after the fasting period.”
This study was led by the University of East Anglia in collaboration with researchers from the Center for Environmental, Fisheries and Aquaculture Sciences (Cefas).
It was carried out with funding from the European Research Council (ERC), the Biotechnology and Biological Sciences Research Council (BBSRC) and the Natural Environment Research Council (NERC).