A new study shows that time-restricted fasting affects reproduction differently in male and female zebrafish. Importantly, some of the negative effects on eggs and sperm quality can be seen after the fish returned to their normal levels of food consumption.
The researchers 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.
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,” said Prof. Alexei Maklakov, from the University of East Anglia, UK.
The research measured how male and female zebrafish allocate resources to body maintenance versus production and maintenance of sperm and eggs, and the quality of the resulting offspring. “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 quality of offspring. The quality of male sperm also decreased,” said Dr. Edward Ivimey-Cook. “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 of the negative effects on eggs and sperm quality can be seen after the animals returned to their normal levels of food consumption following time-restricted fasting.”