Doctors are instructing women to avoid fasting for long periods of time after finding it can trigger fertility complications.
Intermittent fasting can affect certain hormones that manage menstruation in females, health experts have said.
Fasting for long periods of time can cause irregular periods, with some women stopping menstruating all together as a result of not eating for eight to 12 hours per day.
Researchers have also identified a link between intermittent fasting and a higher risk of type 2 diabetes, mental health complications, cardiovascular disease and ovarian cancer.
Intermittent fasting involves switching between fasting and eating on a regular schedule, meaning the body is forced to go hours without any nutrients.
Although this type of eating can be good for weight loss, it commonly disrupts the production of two hormones – luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
These two hormones help the body prepare for ovulation; however, they fail to work correctly when they lack proper nutrients. If these hormones stop functioning, a woman’s periods will stop, making them infertile.
American dietitian Carolyn Williams said: “It’s kind of a cascade of effects on hormones from there.”
TikTok star Sparky told her followers that she stopped having a period in 2021 after frequently fasting before 10am and after 6pm.
The social media influencer said: “’It ruined my hormones. It definitely contributed to my period loss.”
Carolyn noted: “While each person’s calorie needs are unique, less than 1,200 per day is generally considered too few.
“If you’re feeling fatigued, that’s a sign that you’re not eating enough calories. You have to have adequate calories for your body to run.”
She added: “You need to take in adequate calories to actually burn fat. If you don’t take calories your body is going to shut down or slow down everything because it doesn’t know what to do.
“When you are within your eating window, it’s really important to get adequate calories and make sure your food choices are good quality food [and] nutrient-dense food choices.”
She concluded: “It isn’t about drastically cutting calories. It’s more about eating your calories within a specified window so your body has a definite break between your eating window and fasting window.
“If you already have irregular periods or are struggling with infertility, I don’t know that this is the best time to do intermittent fasting. I would check with your doctor because the last thing you want is to disrupt your hormones.”
Intermittent fasting has recently soared in popularity, with there being 1.5 billion views on the topic on TikTok and 5.1 million on Instagram.
