Popular among celebrities like Hugh Jackman, Terry Crews and Kumail Nanjiani, intermittent fasting is a dieting trend that doesn’t seem to be going away any time soon.
But, according to new research conducted by the University of East Anglia, it could have a negative impact on fertility.
Here’s what you need to know.
What is intermittent fasting?
Put simply, intermittent fasting is when you go for extended periods of time without eating, followed by a period of eating normally.
The most common types of intermittent fasting are:
- 5:2 diets – when you consume only 500-600 calories for two days a week. The rest of the week, dieters follow their usual healthy, balanced diets.
- 6:8 plan – when dieters eat for eight hours a day and fast for the remaining 16 hours in a day.
- Alternate day fasting – when dieters fast every other day. Bupa warns that this is difficult to maintain over the longer term.
- 24 hour fasting – when dieters go for 24 hours without eating, often once a week or once a month.
These diets are considered healthier solutions for weight loss, with suggested benefits including improved gut health, reduced blood pressure and better sleep – but as with any diet, they come with certain risks.
Niamh Hennessy, lead dietitian at Cromwell Hospital, warns that for people who are pregnant, have type 1 diabetes, a history of disordered eating or anxiety or depression, fasting isn’t a suitable diet option.
Tests on zebrafish indicate worrying impact on fertility levels
Researchers at the University of East Anglia investigated the impacts of periodically cutting down foods on zebrafish, as they have a similar genetic structure to humans.
They found that egg quality was reduced in females, while the quality of male sperm also decreased.
And once the fish returned to their usual eating habits, the quality of eggs and sperm in the fish did not improve.
Dr Edward Ivimey Cook, from the University’s School of Biological Sciences said: ”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…
“More research is needed to understand how long it takes for sperm and egg quality to return back to normal after the period of fasting.”