Does Intermittent Fasting Affect Female Hormones?

Intermittent fasting has become a popular weight loss option that looks like it's here for the long haul. Focusing on the timeframes of when you can and can’t eat may help you lose weight. It certainly isn’t for everyone and could have negative results for some people. Intermittent fasting could have negative impacts on female hormones.

Key takeaways:
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    Intermittent fasting is a diet method that focuses more on when you should be eating rather than what you should be eating.
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    Intermittent fasting and hormones have been studied in women who were pre and postmenopause.
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    A decrease in weight can directly impact specific hormones (and men’s too).
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    Intermittent fasting has been found to directly affect premenopausal women's hormones. Postmenopausal women had few hormonal changes.
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    Researchers agree not enough studies have been conducted to determine how intermittent fasting could affect women and their hormones on a bigger scale.

What is intermittent fasting?

Intermittent fasting is a diet method that focuses more on when you should be eating rather than what you should be eating. The focus is more on eating during specific times and not eating during other hours to prompt the body burn calories. Despite more recent popularity, intermittent fasting has been used for decades, even before becoming a diet method.

There are several different plans for intermittent fasting. All revolve around the concept of choosing a specific time to eat or not eat every day. Some plans focus on which days to eat or not eat, but the concept is the same.

Plans may restrict eating to:

  • 16/8 – eating healthy during an eight-hour window and fasting for 16 hours.
  • 5:2 – eating healthy for five days, fast for two.
  • Alternate day – eating a normal, healthy diet one day, fasting the next.

During the periods of fasting, the body breaks down fat because it doesn’t have enough glucose. The body uses glucose as fuel. Without glucose, the body can’t create energy.

What are the benefits of intermittent fasting?

Intermittent fasting may have its benefits:

  • Fasting breaks down stored fat.
  • It may also decrease inflammation in the body and lower the stress response.
  • It may help improve memory.
  • Decreasing fat can lead to improving physical performance.

Are female hormones affected?

In recent years, intermittent fasting and hormones have been studied in women who were pre and post-menopause. Women experiencing menopause were not included due to already fluctuating hormones. Studies looked at multiple hormones to see if different types of fasting affected hormone levels compared to women who did not fast.


Weight loss methods, including intermittent fasting, can decrease estrogen in women who are overweight or obese. These women tend to have higher estrogen levels than women who are not overweight.

Higher estrogen levels can be related to increased adipose or fat tissue. As a result, women who are obese are at increased risk of polycystic ovarian syndrome (PCOS), breast cancer, or not ovulating (anovulation).

Sex hormone-binding globulin

Sex hormone-binding globulin (SHBG) is a protein that moves testosterone and estrogen to the places that need them. SHBG was shown to increase in women who use intermittent fasting. This is beneficial, especially in women with PCOS. Women who ate mostly in the morning or afternoon were found to have the most benefit.


Prolactin is a hormone directly related to breast milk production and breast development. Only one study has been conducted on prolactin. Results show that levels did not change during intermittent fasting.


Gonadotropins control ovarian function, normal growth, reproduction, and sexual development. These hormones include follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Only one intermittent fasting study was conducted, and results showed FSH and LH did not unchanged after small amounts of weight loss. However, other studies on weight loss have noted LH/FSH ratio decreases with weight loss. This can affect female egg maturity, possibly putting fertility at risk.


Androgens are hormones including testosterone, dehydroepiandrosterone-sulfate (DHEA-S), and androstenedione. Yes, women have testosterone.

High androgen, or hyperandrogenism, is a medical condition where these hormones are high. It causes hirsutism in females (excessive hair male-like growth), seborrhea (a scaly, itchy rash), and abnormal menstrual cycles. There is also a link to insulin resistance.

Weight loss with intermittent fasting can decrease androgen levels in obese women. These changes also occurred in women with PCOS, especially when most of the calories were eaten early in the day.

Is it the same after menopause?

Similar concerns were raised in women who have already experienced menopause. Does intermittent fasting affect the hormones of postmenopausal women?

Studies show that testosterone, androstenedione, and sex hormone-binding globulin levels did not change with weight loss from intermittent fasting. Estrogen and progesterone were also unchanged. However, DHEA decreased in postmenopausal women who lost weight.

What does it all mean?

Intermittent fasting may benefit some women who are working to lose weight. It might also help women who have health issues like PCOS, insulin resistance, fertility issues, and menstrual irregularities related to obesity.

Researchers agree not enough studies have been conducted to determine how intermittent fasting could affect women and their hormones on a bigger scale.

Men can be affected too

Like the women who were observed during and after intermittent fasting, groups of men were monitored as well for hormone changes. In the male study, a group of men who followed intermittent fasting was compared to a group who followed a regular diet.

The results showed decreased testosterone, insulin, and glucose in the men who fasted. This group was also found to have a decrease in T3, a thyroid hormone that helps regulate the heart, brain, muscles, and other body functions.

Should I try fasting?

Studies show that a decrease in weight can directly impact specific hormones. Women with these health issues should contact their healthcare provider to see if intermittent fasting is a good option. While some women may benefit from decreasing certain hormones, other women will not.

Fasting is not a good choice for everyone. People with certain health issues should not use intermittent fasting. Do not try fasting if you are:

  • A Type 1 diabetic
  • Pregnant or breastfeeding
  • A person with a history of eating disorder
  • A child or a teenager

Athletes may also find intermittent fasting does not work well for them. It does not allow them to refuel properly. They don’t get enough calories for what their active bodies need.

Intermittent fasting has a direct effect on women's hormones. Women who are overweight or obese can have health problems related to their weight. Intermittent fasting can help with health problems like PCOS, menstrual irregularities, and fertility issues.

Further studies are necessary to determine if intermittent fasting would be beneficial overall. Some hormone levels changed, and some did not. Some changes were beneficial and some were not. The results appear to be mostly positive.


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