In recent years, intermittent fasting (IF) has gained increasing popularity. Unlike most diets prescribing what to eat, IF emphasizes when to eat through the incorporation of regular short-term fasts into your routine. This approach may aid in consuming fewer calories, losing weight, and reducing the risk of diabetes and heart disease.

However, several studies have suggested that IF may not offer the same benefits to women as it does to men. Therefore, women may need to adopt a modified approach.

What is IF?

IF is an eating pattern characterized by alternating periods of abstaining from food and eating.

Unlike most diets, IF does not entail monitoring calories or macronutrients. In fact, there are no mandates regarding food choices or restrictions, rendering it more of a lifestyle than a diet.

Intermittent Fasting Plan

The most common methods include fasting every other day, fasting for 16 hours each day, or fasting for 24 hours twice a week.

Other less popular approaches are the  B2 regimen with 2 large meals per day with a 14-hour fast and weekly one-day fasting.

Benefits For IF in Women 

Women can derive many of the same benefits from IF as men. It not only contributes to a healthier waistline but may also decrease the risk of developing various chronic diseases.

Weight Loss

Several studies indicate that IF equals traditional calorie-restricted diets in effectiveness for short-term weight loss.

In a 2022 trial, researchers discovered that short-term IF benefited overweight men and women in optimizing weight and body composition.

A 2018 review of studies involving overweight adults revealed that IF resulted in an average weight loss of 15 lbs (6.8 kg) over 3–12 months.

It’s important to acknowledge that the long-term impact of IF on weight loss for women is yet to be determined.

Heart Health

A 2021 review suggested that IF could enhance several indicators of metabolic health. According to the review, IF may reduce blood pressure, insulin resistance, and oxidative stress, potentially benefiting cardiometabolic health. It also noted decreases in low-density lipoprotein cholesterol and triglyceride levels, although findings varied.

Diabetes

IF may also effectively aid in managing and decreasing your risk of developing diabetes.

Similar to continuous calorie restriction, IF appears to decrease certain risk factors for diabetes. This effect primarily occurs by lowering insulin levels and reducing insulin resistance.

In a 2011 randomized controlled study involving over 100 overweight or obese women, six months of IF resulted in a 29% reduction in insulin levels and a 19% decrease in insulin resistance. Blood sugar levels remained unchanged.

However, researchers need to conduct more robust studies to draw better conclusions.

Other health benefits

Several human and animal studies suggest that IF may also produce other health benefits.

• Decreased Appetite: Some studies suggest that IF can reduce appetite.
• Reduced inflammation: Some studies indicate that IF can reduce key markers of inflammation. Chronic inflammation, which can result in weight gain and various health problems, may be mitigated.
• Increased longevity: IF has demonstrated an extension of lifespan in rats and mice. However, the effects on human longevity are yet to be determined.
• Preserved muscle mass: IF appears to be more effective at preserving muscle mass compared to continuous calorie restriction. Higher muscle mass contributes to increased calorie burning, even at rest.

Specifically, the health benefits of IF for women require further exploration in well-designed human studies before any definitive conclusions can be drawn.

Effect of Intermittent Fasting on Hormones in Women

There are numerous anecdotal accounts of women reporting changes to their menstrual cycles upon starting IF.

These changes occur because female bodies are highly sensitive to calorie restriction.

When calorie intake is low—such as during prolonged or frequent fasting—a small part of the brain called the hypothalamus is affected.

This disruption can interfere with the secretion of gonadotropin-releasing hormone (GnRH), which regulates the release of two reproductive hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

When communication between these hormones and the ovaries is disrupted, it can lead to irregular periods, infertility, poor bone health, and other health issues.

However, a review published in 2022 found that IF lowers certain hormone levels associated with male characteristics (like testosterone and the free androgen index) while raising levels of another protein called sex hormone-binding globulin (SHBG) in premenopausal women who are obese. This tends to happen more when you eat all your food earlier in the day, stopping eating by 4 pm. However, fasting did not seem to change levels of estrogen, gonadotropins, or prolactin in women.

A small-scale 2021 study involving 18 women aged 18–31 with PCOS over a 6-week period showed significant improvements in menstrual cycle regularity and reduced body fat, among other positive outcomes.

Due to these considerations, women should contemplate adopting a modified approach toIF, such as shorter fasting periods, fewer fasting days, and different fasting patterns.

Intermittent Fasting Schedule For Women

If you’re pregnant, breastfeeding (chestfeeding), or trying to conceive, IF isn’t recommended. But for other females who are pre-menopausal, you may be able to reap some of the benefits of IF without a major impact on your hormones. But you should consider following these measures for a healthy IF schedule.

Avoid Going To Extreme

Several different approaches exist for IF with some being more intense than others.

Some individuals choose to limit their eating to specific hours each day, while others follow a regular eating pattern on certain days of the week and severely restrict their calorie intake on other days.

Experts recommend that pre-menopausal females, especially beginners, may benefit from starting with a low-intensity IF schedule. Starting with a 12-hour fasting window is suggested as a safe starting point for most people.

For instance, one could begin by fasting from 8 p.m. in the evening until 8 a.m. the next morning.

If this initial schedule is successful after a week, individuals can gradually extend the fasting period by two hours, adding an hour of fasting before or after the designated window.

Right Times To Fast

It’s advisable to try fasting a day or two after your period starts and again about a week later. During the two weeks before your period is expected, it’s recommended to restrict fasting times. The period around ovulation, occurring approximately two weeks before your period is when your hormones are most susceptible to the effects of fasting.

It’s best to refrain from fasting during the week leading up to your period, as this is when your body is most sensitive to stress. Estrogen levels drop during this time, making your body more sensitive to cortisol, the stress hormone.

Healthy Eating Practices

IF primarily emphasizes the timing of meals, but the content of your diet remains crucial.

Experts recommend reducing intake of processed and packaged foods and opting for lean proteins, fruits, vegetables, and whole grains.

When breaking a fast, it’s essential to choose your first meal wisely. You should break your fast with a meal high in protein, fiber, and healthy fats. This will help prevent a significant spike in blood sugar.

Additionally, it’s important not to rush through your meal. Take your time and savor your food after fasting.

Consult a Healthcare Provider

Planning and adhering to an IF eating plan can pose challenges. It’s crucial to ensure that your efforts align with your goals without causing significant impacts on your hormones and overall health.

Seek guidance from a healthcare provider, such as a registered dietitian, before embarking on an IF regimen. They can assist in comprehending your health objectives and provide healthy approaches to achieve them.

Summary

Intermittent fasting is a dietary pattern that involves regular, short-term fasts. While IF is beneficial for heart health, diabetes, and weight loss, some evidence indicates it may negatively affect reproduction and blood sugar levels in some women.

That being said, modified versions of IF appear safe for most women and maybe a more suitable option than longer or stricter fasts.

References

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2. Cienfuegos S;Corapi S;Gabel K;Ezpeleta M;Kalam F;Lin S;Pavlou V;Varady KA; (n.d.). Effect of intermittent fasting on reproductive hormone levels in females and males: A review of human trials. Nutrients. https://pubmed.ncbi.nlm.nih.gov/35684143/ 
3. Cleveland Clinic. (2023, December 21). Why intermittent fasting may be less effective for some women. https://health.clevelandclinic.org/intermittent-fasting-for-women 
4. Coyle, D. (2023, December 6). Intermittent fasting for women: A beginner’s guide. Healthline. https://www.healthline.com/nutrition/intermittent-fasting-for-women 
5. Dong, T. A., Sandesara, P. B., Dhindsa, D. S., Mehta, A., Arneson, L. C., Dollar, A. L., Taub, P. R., & Sperling, L. S. (2020, August). Intermittent fasting: A heart healthy dietary pattern?. The American journal of medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7415631/ 
6. Varady, K. A., Cienfuegos, S., Ezpeleta, M., & Gabel, K. (2021). Cardiometabolic benefits of intermittent fasting. Annual Review of Nutrition, 41(1), 333–361. https://doi.org/10.1146/annurev-nutr-052020-041327