Fasting Safely: Advice for Women, Hormones, and Weight Loss

Intermittent fasting has an impressively long and diverse list of benefits from reducing body fat and inflammation, to improving cardiovascular health and metabolism. But for women seeking to harness the power of fasting to support hormonal balance and weight loss goals, it’s essential to understand both the potential benefits and potential risks. After reading, you’ll understand how you can use intermittent fasting safely and effectively while keeping in mind the unique considerations related to hormone health and metabolism.

If you’re here, it’s likely that one of two things is true:

  1. You’ve decided to start intermittent fasting to improve your health, but you want to make sure it’s not going to cause problems for your hormones, or
  2. You want to start fasting, but you’re not sure it’s safe

Either way, you need to know what the risks are for women specifically, because your body is different from a man’s—and so is your response to fasting!

(Note: No matter where you are on your journey, the supportive community inside the Superwoman Circle will help you reach your goals.)

Understanding Intermittent Fasting and Its Impact on Women’s Health

Intermittent fasting (IF) involves alternating periods of eating and fasting, with the aim of allowing the body to tap into its energy reserves and promote various physiological benefits. For women, however, it’s crucial to approach fasting with a nuanced understanding of how it can impact hormonal health.

The problem with most IF protocols is they approach every body as if they’re the same (most fitness and weight loss plans are like this, and as I’ve said before, individualized plans are the holy grail when it comes to health!).

A one-size-fits-all approach to fasting is a problem because:

  • Most research on fasting is done using healthy men (not women!)
  • Women’s hormones fluctuate on a daily and monthly basis
  • Female bodies are more sensitive to metabolic distress

Related: Learn more about intermittent fasting with Dr. Taz & Cynthia Thurlow, NP.

Who should do extra research before fasting?

Women who are trying to conceive

Some small studies show that certain types of intermittent fasting can affect hormones related to fertility. Generally, shorter fasts are ok, but longer fasting windows may have negative effects for some women.

In women with obesity, one study found that a very restrictive fast (an eating window of only 4–6 hours) reduced levels of DHEA, a hormone that’s needed to create both estrogen and testosterone (1).

If you’re trying for a baby, research suggests you’re better off sticking to more moderate intermittent fasting types, such as a 16:8 fast (2).

Related: Everything You Need to Know About Prenatals with Julie Sawaya

If you struggle or have struggled with an eating disorder

Intermittent fasting can help improve metabolism and aid weight loss, but it should be approached with caution by those with a history of disordered eating. Intermittent fasting has the potential to trigger unhealthy behavior patterns in those with a history of disordered eating.

Disordered eating is defined as any type of irregular or abnormal patterns of food consumption which may lead to physical or psychological issues. This could include binge-eating disorder, orthorexia, anorexia nervosa, bulimia, and more.

Women who experienced metabolic distress

Women with hypothyroidism or adrenal fatigue, as well as those who are already underweight should also approach intermittent fasting cautiously. These conditions can be caused by prolonged periods of stress and often lead to metabolic issues.

Metabolic distress is defined as an imbalance between the body’s energy intake (food) and its ability to use that energy. Generally, if the body is unable to effectively process food, then it won’t be able to create and utilize hormones properly.

Read: 7 Signs You’re on the Road to Burnout

Women over the age of 40

Some evidence suggests that women over the age of 40 may not respond as well to intermittent fasting. This is mainly due to the natural decline in hormone levels and lean muscle mass that occurs with age, which can further complicate metabolic issues (3,4). What’s more, fasting usually makes it much more difficult to consume adequate amounts of protein, further contributing to loss of muscle and slowing metabolism overall. 

It’s important for women over 40 to emphasize regular and adequate nutrition and protein during eating windows, and monitor their body’s response to fasting.

The Potential Negative Health Impacts of Fasting for Women

Hormonal Imbalance

Hormones like estrogen, progesterone, and testosterone are sensitive to big changes in calorie intake, and prolonged or extreme fasting can disrupt hormonal balance, leading to irregular menstrual cycles, decreased fertility, and potentially exacerbating preexisting hormone-related conditions (5).

However, some types of fasting—when practiced safely—are beneficial for hormone health, reducing inflammation and helping to regulate menstrual cycles.

Thyroid Function

Intermittent fasting may reduce the production of thyroid hormones, which are critical for maintaining metabolism and energy levels.

For example, fasting results in an increase in your inactive thyroid hormone (rT3), which then competes with active T3 to bind to receptors (6). However, studies also show that both levels return to pre-fast levels after breaking your fast with a balanced meal. 

Adrenal Stress

Prolonged fasting can lead to increased cortisol production, placing additional stress on the adrenal glands, potentially affecting energy levels and sleep patterns (7). 

Shorter fasts likely help normalize cortisol levels, especially in women who are overweight or obese. However, it’s important to be aware that your experience may differ.

If you’re experiencing fatigue, difficulty losing weight, or changes in mood, you may need to address potential adrenal dysfunction before beginning intermittent fasting.

Related: How to Fix Adrenal Fatigue and Cortisol Dysfunction in Women

Mental Health

Research shows that while fasting can lead to negative emotional states, such as anger or irritability, it can also result in positive states, like self-acceptance or a sense of accomplishment (8). 

One 2022 review shows mixed evidence for fasting, with both negative and positive effects (9). It’s important to be mindful of potential triggers and monitor one’s mental health closely when practicing IF.

The Benefits of Fasting for Women

While there are potential risks associated with fasting for women, when approached responsibly, intermittent fasting can offer several benefits that support overall well-being (10): 

Weight Loss and Metabolic Benefits: Intermittent fasting can promote weight loss by facilitating fat burning and improving insulin sensitivity, making it an effective tool for women seeking to manage their weight.

PCOS Symptom Management: One 2023 study evaluating the effect of a 16:8 fast (a 16-hour fast and an 8-hour eating window) in women with PCOS showed a normalization of androgen levels and improved insulin resistance, as well as a reduction in BMI and body fat percentage (11).

Cellular Repair and Longevity: Fasting triggers a process called autophagy, which allows cells to remove damaged components and may contribute to enhanced cellular repair and anti-aging effects.

Improved Brain Function: Some studies suggest that intermittent fasting may support cognitive function and brain health by promoting the production of brain-derived neurotrophic factor (BDNF).

Simplified Eating Patterns: For some women, intermittent fasting can simplify meal planning and reduce mindless snacking, promoting mindful eating habits.

Related: How to Intermittent Fast + 6 Tips to Get Started

Utilizing Intermittent Fasting Safely for Women’s Health Goals: Do’s & Don’ts

For women looking to incorporate intermittent fasting into their lifestyle while maintaining hormonal balance and overall health, consider the following strategies:

  • Don’t force a fast. Avoid diving into intense fasting schedules right away. Begin with shorter fasting windows and gradually increase the duration over time.
  • Listen to your body: If you experience negative symptoms or disruptions in your menstrual cycle, consider modifying your fasting approach or seeking guidance from a healthcare professional.
  • Customize fasting to your needs: Tailor your fasting schedule to suit your unique needs, considering factors like age, menstrual cycle phase, and special metabolic conditions. (Note: Fasting may not be recommended for some kinds of metabolic disorders. Speak with a qualified holistic or integrative doctor first.)
  • Stay hydrated: Hydration is essential during fasting periods. Ensure you drink plenty of water and consider herbal teas or electrolyte-rich beverages to support hydration.
  • Don’t break your fast with junk food: When breaking your fast, focus on nutrient-dense foods to nourish your body effectively. A poorly balanced meal won’t serve you any better after a fast than it would if you had not fasted at all.
  • Prioritize sleep and stress management: Quality sleep and stress reduction are vital for hormonal balance. Prioritize rest and relaxation during fasting and non-fasting periods.

Empowering Women on A Fasting Journey

Intermittent fasting can be a powerful tool for women aiming to achieve their health and weight loss goals, but it requires a thoughtful and individualized approach. By understanding the potential risks and benefits of fasting, customizing fasting schedules to individual needs, and prioritizing hormonal balance and overall health, women can safely harness the transformative power of intermittent fasting.

Remember, every woman’s body is unique, so it’s essential to consult with a healthcare professional before embarking on any fasting regimen to ensure it aligns with your health and wellness objectives.


Dr. Taz Bhatia M.D.