Researchers have found that time-restricted fasting could cause fertility problems. 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 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 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.