Millions of women are at risk of little-known side effect of intermittent fasting that could lead to infertility, doctors warn

Intermittent fasting has been hailed as the miracle cure for weight loss in recent years, but doctors warn millions of women should avoid it.

It’s estimated that one in ten Americans follow the diet—which involves eating within a strict time frame to reduce the amount of calories one consumes.

However, experts told DailyMail.com that prolonged fasting can affect the hormones that regulate menstruation in women.

This can lead to irregular periods, which have been linked to a higher risk of ovarian cancer, heart disease, type 2 diabetes and mental health problems.

Some women say they stop menstruating altogether if they fast for eight to 12 hours a day.

Jennifer Aniston (left) and Nicole Kidman (right) are two celebrities who reportedly followed an intermittent fasting regimen

Carolyn Williams, an Alabama dietitian, recommends choosing nutrient-dense foods like lean meats, leafy greens, and whole grains during the eating window to avoid hormonal imbalances

While intermittent fasting, which alternates between days of fasting and days of eating normally, can be great for weight loss, it forces the body to go without nutrients for long periods of time. This can lead to hormonal deficiencies, causing menstrual cycles to become irregular or stop altogether.

Fasting too long or too often can disrupt the production of two hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

Both are secreted by the pituitary gland in the hypothalamus, which acts as the control center of the brain.

LH and FSH regulate the menstrual cycle by preparing the body for ovulation, with the ovary releasing a mature egg.

Too many restrictions can hinder these processes, as hormones cannot function properly without the right nutrients.

Without these hormones, women are more likely to experience irregular periods and, more rarely, interfile. This is because women without periods cannot ovulate, which reduces their chances of getting pregnant.

“From there, it’s kind of a cascade of effects on hormones,” Carolyn Williams, an Alabama dietitian, told DailyMail.com.

Following an intermittent fasting regimen involves alternating between days of fasting and days of normal eating. On fasting days, dieters restrict their eating to certain windows during the day, such as eating only at breakfast or dinner.

Intermittent fasting diets generally fall into two categories: the 16:8 diet and the 5:2 diet. These regimens limit eating times to a period of 6 to 8 hours per day or severely restrict calories on certain days.

Followers of the 16:8 diet fast for 16 hours a day and eat whatever they want in the remaining eight hours — usually between 10 a.m. and 6 p.m.

On the 5:2 diet, people limit their calories to between 500 and 600 per day for two days a week and eat normally for the remaining five days.

TikTokers Sparky (left) and Kristine Crouch (right) shared that fasting made their periods irregular or caused them to stop altogether

A TikToker with the username Sparky shared that she stopped having her menstrual cycle in 2021. At that time, she regularly fasted before 10 a.m. and after 6 p.m.

“It messed up my hormones,” she said. “It definitely contributed to my menstrual loss.”

In April, fasting expert Kristine Crouch posted a TikTok video explaining how she stopped menstruating during an extended fast.

“After my fast, when I came out, I got my period and it’s been so regular for years and years and years.”

Ms Williams said that while each person’s calorie needs are unique, less than 1,200 a day is generally considered too little.

“If you feel fatigued, it’s a sign you’re not getting enough calories.” You have to have enough calories to keep your body working,” said Ms. Williams.

“You have to get enough calories to actually burn fat. If you don’t take in calories, your body will shut down or slow down because it doesn’t know what to do.’

Eating nutritious foods during your eating period is key to avoiding these hormonal drawbacks. This includes foods rich in fiber, protein, fatty acids such as omega-3s, and vitamins.

Ms. Williams suggests opting for lean proteins such as chicken or turkey, nuts and seeds, fruits and dark leafy greens, and beans and lentils.

“When you’re within your eating window, it’s really important to get enough calories and make sure your food choices are good quality food(s) that are nutritious,” she said.

“IF is not about drastically cutting calories. It’s more about eating your calories within a certain window so that your body has a clear break between your eating and fasting windows.”

However, Ms. Williams does not recommend the diet if you already have irregular periods.

“If you already have irregular periods or are struggling with infertility, I don’t know if this is the best time to do intermittent fasting,” she said.

“I’d talk to your GP because the last thing you want is to disrupt your hormones.”

She also suggested avoiding intermittent fasting if you’re pregnant, trying to conceive, or have a history of eating disorders.

While fasting is hardly a new concept, it has received a lot of attention in recent years.

Intermittent fasting has 1.5 billion views on TikTok and 5.1 million posts on Instagram. In addition, a survey last year by the International Food Information Council found that one in 10 Americans follows the diet.

However, its efficacy has also been much debated.

This is according to a study published last year in the Journal of Clinical Endocrinology & Metabolismfor example, researchers studied 36 diabetic patients for three months. They found that nearly 90 percent, including those taking insulin, were able to reduce the amount of diabetes medication they were taking.

In addition, a 2017 study found that two weeks of intermittent fasting led to significant weight loss and improved glucose levels.

However, a study published in June found that while intermittent fasting did help patients lose weight, it was no more effective than basic calorie counting.

In some cases, intermittent fasting may actually improve hormone levels in women. Women with polycystic ovary syndrome (PCOS), a condition that causes high levels of the male hormone androgens, resulting in irregular periods, could benefit from the diet.

“They usually have higher levels of androgens and testosterone, which is why intermittent fasting can lower those levels, which can help with their menstrual cycle regularity,” said Ms Williams.