As a woman in her early 40s, you may have noticed a change in your monthly cycle. It might have gotten either longer or shorter, or you may have even experienced a major shift in how you feel throughout the month. This is perfectly normal and is often a part of aging. It could be the sign of perimenopause, which is the very earliest stage of menopause, where your hormones first begin to shift. This can happen quite a few years before true menopause sets in. These hormone changes can feel challenging for many women, and it’s natural for them to feel a bit scared at first. But the good news is that there are a lot of ways to support your body during this time. One of my favorite tools is intermittent fasting. It’s simple and effective, helping to bring balance and ease some of the more difficult side effects of these changes. By taking a closer look at how intermittent fasting works, you can better navigate the shifts that perimenopause brings.
What Is Perimenopause?
Perimenopause is the natural phase that marks the transition into menopause. For most women, this begins between the ages of 40-44, but it can start as early as 35 or as late as 50. During this time, your ovaries start making less estrogen and progesterone, which can cause your menstrual cycle to become irregular. It may lengthen, shorten, or even stop for a few months before starting again. While this is a healthy part of aging, it can be a challenging time as your body adjusts. Having a lot of knowledge about what to expect can make this phase easier to navigate.
Symptoms of Perimenopause:
Perimenopause is often marked by a range of physical and emotional symptoms as your hormones, particularly estrogen and progesterone, start to fluctuate. These hormonal changes can bring night sweats, hot flashes, and trouble sleeping, which leave many women feeling fatigued and irritable. It’s not uncommon to experience increased anxiety, mood swings, and even headaches during this transition period. Additionally, vaginal dryness and changes in libido can occur as your body’s needs begin to shift. While these symptoms can be unsettling, it’s important to remember that this is a perfectly normal part of the perimenopausal years as your body adjusts to these changes.
In this stage, which typically begins in a woman’s 40s, the ovaries produce less estrogen and progesterone, leading to irregular periods that can become lighter, heavier, or occur more or less frequently. These hormonal fluctuations are the hallmark of perimenopause and can last a few years or even over a decade. Along with the erratic hormone production, you may notice weight gain around the abdomen, hair changes, and shifts in skin texture. Fertility declines during this time as ovulation becomes less predictable, making conception more difficult. However, contraceptive measures should still be considered until menopause is confirmed after 12 consecutive months without a menstrual period.
The long-term health concerns tied to the reduction of estrogen levels are also important to consider. A decrease in bone density can increase the risk of osteoporosis, and cardiovascular disease becomes more of a concern as blood pressure and cholesterol levels may rise. Understanding these changes and finding ways to support your body during this time can significantly improve your quality of life as you navigate through perimenopause and approach menopause.
What Is Intermittent Fasting?
For many of my perimenopausal clients, intermittent fasting has proven to be one of the most effective tools for managing symptoms. The idea behind intermittent fasting is simple—it involves going without food for a certain portion of the day, allowing your body to rest and digest. The most common approach is the 16:8 fast, where you fast for 16 hours and eat during an 8-hour window, like from 12 PM to 8 PM. Some people prefer the One Meal A Day (OMAD) method, having a single big meal (usually dinner) and fasting for the rest of the day. For others, shorter fasts like 14 hours or longer fasts like 48-hour fasts can work as well, depending on what feels right for their bodies.
There are also different ways to approach intermittent fasting, such as time-restricted feeding, which focuses on eating during specific windows, or the 5:2 diet, where you consume 500-600 calories on two days of the week while eating normally on the other five days. More hardcore methods like alternate-day fasting, where you limit food to 500 calories every other day, can be challenging but effective for some. Whether you choose a 16:8 protocol or try something like the 5:2 diet, the key is to find a method that works for you and supports your body through the changes of perimenopause.
What Are the Benefits of Intermittent Fasting?
Intermittent fasting (IF) offers dozens of benefits, making it an excellent option for perimenopausal women. One of the most notable advantages is weight loss, especially when managing weight gain becomes a concern during this stage. By controlling when and how you eat, fasting can help reduce belly fat, improve insulin sensitivity, and balance blood sugar levels. This is particularly important as hormonal changes during perimenopause can lead to increased fat around the middle, along with a decrease in metabolism. IF also helps in improving glucose tolerance, lowering blood glucose levels, and reducing the risk of type 2 diabetes—factors that become more relevant as we age.
Another key benefit of intermittent fasting is its ability to lower inflammation in the body. Chronic inflammation can lead to various health issues, including heart disease and even cancer. By practicing IF, your body gets a chance to reset, reducing the overactivity of white blood cells that can attack healthy tissue. A small study combining intermittent fasting with protein pacing over 8 weeks showed a significant improvement in both gastrointestinal symptoms and metabolic health, which can be especially beneficial during perimenopause. Research also points to reduced hot flashes, improved mood swings, and an overall better quality of life during this transition.
From a metabolic perspective, fasting triggers your body to shift from using glucose as its primary fuel source to breaking down fat for energy, producing ketones in the process. These ketones become the body’s alternative energy supply, especially during a fast that lasts 12-36 hours. When the body reaches ketosis, it begins to burn fat more efficiently. This metabolic shift not only helps with weight loss but also promotes healthy aging by supporting brain health, and mental clarity, and increasing overall energy levels.
In addition to physical benefits, intermittent fasting has a positive impact on mental health. Many women in their perimenopausal years experience heightened anxiety and depression due to the emotional shifts tied to hormonal fluctuations. IF has been shown to help stabilize these mood swings by reducing inflammation and supporting better brain health, making it easier to manage the emotional roller coaster that often accompanies this phase of life.
How Fasting Can Help with Perimenopause:
Days 1-10: Building Estrogen with Longer Fasts:
During perimenopause, as your hormones like estrogen and progesterone fluctuate, incorporating longer fasts can be an effective way to support and balance your body. When your estrogen levels are low—particularly in the early days 1-10 of your menstrual cycle—this is the perfect time to engage in a longer fast of 20 to 48 hours. This fasting strategy can help your body recover from inflammation, and leave you feeling both mentally and physically strong as you enter the next phase of your cycle. By timing your fasts during this estrogen-building phase, you can give your body the break it needs to stay steady and avoid the rollercoaster of hormonal decline that often accompanies perimenopause.
Days 11-15: Supporting Ovulation with Shorter Fasts:
During days 11-15, which is around the time of ovulation, your estrogen levels peak, and progesterone begins to rise. For perimenopausal women, this hormonal shift can make longer fasting more challenging, leading to feelings of being cranky or low in energy. This is when shorter fasts of around 15 hours per day can be more beneficial. These anti-inflammatory and energy-enhancing shorter fasts allow you to still reap the benefits of fasting without overtaxing your body. As progesterone increases, it’s important to listen to your body and ease off if fasting feels harder during this middle part of your cycle, while still enjoying the energy and anti-inflammatory effects of a gentle, shorter fasting routine.
Day 16-19: Longer Fasts:
As you move into days 16-19 of your cycle, your hormones dip and this energy phase makes it a great time to incorporate longer fasts. During this stage, your energy may begin to decrease, but doing a 24-hour fast can feel surprisingly easy. Fasting during this time helps reduce inflammation and allows your body to prepare for the last phase of the cycle. By embracing fasting when your hormones dip, you can better manage low energy levels and support your body as it moves into the final phase of the cycle.
Day 20-End: Feasting to Nourish Your Body:
In the final phase of your cycle, progesterone continues to increase, often causing bloating, cramps, and fatigue. While fasting might have worked well in the earlier part of the cycle, now is the time to focus on nourishing your body with whole foods. Incorporate nutrient-rich options like sweet potatoes, and butternut squash, healthy fats such as grass-fed butter and olive oil, as well as red meat, fatty fish, and plenty of green vegetables and fruit. This is the time when your body benefits from extra care, as your hormones shift between estrogen and progesterone. Many of my clients have found that adopting a balanced approach with fasting and feasting during perimenopause makes a significant difference in how they feel during this phase, allowing them to rest and nourish their bodies effectively.
How Intermittent Fasting Can Influence Hormonal Health:
Intermittent fasting has been shown to impact hormonal health in a variety of ways, especially for women going through perimenopause. Research led by Krista Varady, a professor of nutrition at the University of Illinois Chicago, examined how intermittent fasting could change the levels of certain female reproductive hormones. In an eight-week study funded by the National Institute of Diabetes, Digestive, and Kidney Diseases, pre-menopausal and post-menopausal obese women followed an intermittent fasting diet. They ate during a restricted window—either a four-hour or six-hour period—without limiting calories while drinking water during fasting times. The results showed no significant differences in hormone levels between those who followed the diet and a control group that did not have any diet restrictions.
In this study, reproductive hormones like testosterone, estrogen, and DHEA (a steroid hormone) remained unchanged in the women who followed the fasting routine. This suggests that intermittent fasting, even over eight weeks, does not negatively affect hormone production. The participants who fasted did experience a drop in insulin resistance and biomarkers of oxidative stress, which are important for overall health. These benefits, combined with the fact that the participants lost 3% to 4% of their baseline weight, suggest that intermittent fasting is a safe and effective method for improving metabolic health without disturbing the normal levels of key reproductive hormones.
Other studies and experiences from thousands of women show that alternate-day fasting and time-restricted eating strategies can help women eat less by shortening their eating windows. This naturally leads to a reduction in calorie intake, which supports weight loss and potentially improves conditions like insulin resistance. However, in the research conducted by Krista Varady, no significant changes were found in the sex-binding globulin or protein that carries reproductive hormones such as testosterone and androstenedione, highlighting that intermittent fasting can help with weight loss while keeping hormonal balance intact.
Although some studies in mice and rats have raised concerns about the potential negative effects of intermittent fasting on reproductive hormones, human research, like the study from the University of Illinois Chicago, provides reassuring evidence. In women, particularly those who are pre-menopausal or post-menopausal, intermittent fasting seems to be a useful tool for weight management and metabolic health without harming ovarian function or hormone production. This makes it a promising strategy for women in their perimenopausal years who are looking to improve their health through fasting.
Are There Any Downsides Of Intermittent Fasting During Perimenopause?
For some perimenopausal women, the natural hormone changes combined with fasting can be challenging. During the perimenopausal journey, your body is already under stress, and fasting for extended periods may increase your stress response, causing a rise in cortisol, the stress hormone. This spike in cortisol can make your body more prone to inflammation and feel less resilient, leading to feelings of low energy and low mood. In this stage of life, restricting food intake too much can also lead to cravings and negative relationships with food and your body.
One of the major concerns during perimenopause is maintaining lean muscle mass, which can naturally decline due to hormonal shifts. Intermittent fasting may contribute to muscle loss, especially if fasting is done for long periods or without sufficient physical activity. While fasting helps with weight loss, it can result in an equal loss of fat stores and lean muscle mass, which is not ideal during this time when building and maintaining muscle should be a top priority. It can also be hard to stick to fasting days when energy levels dip, making it difficult to balance muscle maintenance with fasting strategies.
Challenges and Considerations for Intermittent Fasting in Perimenopause:
While intermittent fasting offers many potential benefits for women in perimenopause, there are important challenges and considerations to keep in mind. As women navigate this transitional phase, marked by significant hormonal changes, it’s crucial to understand how fasting might affect their bodies. Perimenopause is often associated with mood swings, insomnia, and increased anxiety, all of which can be worsened if fasting leads to additional stress on the body. Hormonal fluctuations during this time can make women more sensitive to changes, so ensuring that fasting is done in a way that is both safe and effective is essential.
One key consideration is the body’s changing nutritional needs during perimenopause. As estrogen levels decline, women are at a higher risk of bone density loss, making it important to get enough calcium, vitamin D, and magnesium. When practicing intermittent fasting, women should ensure that their eating periods include a nutrient-dense diet to support bone health. The risk of reduced bone density is a major concern, especially if reduced food intake leads to inadequate nutrition. Fasting periods should be carefully managed, and women should monitor their bone health while fasting to prevent any long-term effects.
Another challenge during perimenopause is the natural slowing of metabolism, which can affect how the body responds to intermittent fasting. What may have worked in earlier years might now feel less effective or even more difficult to tolerate. This phase of life often comes with significant emotional fluctuations, making it mentally challenging to stick to a new fasting schedule. There’s also the issue of social and family life—adjusting meal timings to fit with fasting windows can interfere with social interactions and family meals, which are important parts of many women’s lives. Finding a balance between fasting and maintaining these social commitments can be difficult, but it’s important for long-term success.
Lastly, before starting any intermittent fasting regimen, women in perimenopause should consult with their healthcare providers. This ensures that the fasting approach is tailored to their specific health conditions and lifestyle needs. Consultation helps address any challenges and ensures that fasting is safe during this transitional phase. By working with a healthcare provider, women can better navigate the balance between fasting, health, and their everyday lives, making intermittent fasting more manageable and beneficial.
Intermittent Fasting During Perimenopause Tips:
For women’s hormonal health during perimenopause, practicing intermittent fasting can be beneficial, but it’s important to approach it carefully. One of the best tips is to start by reviewing your current eating habits. Take a few days to record the times you are eating during a normal 24-hour period. This will help you tune into your body’s needs and identify if you’re a late-night snacker or someone who needs breakfast as soon as you wake up. Once you understand your current eating patterns, you can begin to create a longer fasting window that works for you. For example, try moving your evening meal an hour earlier to give your body more time to rest and digest before bedtime.
When starting intermittent fasting, it’s crucial to listen to your body’s cues and start gradually. A gentle way to begin is the 12:12 method, where you fast for 12 hours and have a 12-hour eating window. As your body adjusts, you can slowly move toward a more structured approach like the 16:8 protocol, where you fast for 16 hours and eat within an 8-hour window. For some, One Meal A Day (OMAD) can work, but it’s important to find what’s right for your body without causing significant stress.
Hydration is another key factor when fasting, especially during fasting periods. Make sure you stay well-hydrated by drinking water, herbal teas, or other non-caloric beverages. This will help prevent dehydration, which is a common issue when people first start fasting. In your eating windows, focus on nutrient-dense foods that provide the necessary vitamins, minerals, and nutrients. A good balance of protein, healthy fats, and fiber from whole foods like vegetables, fruits, nuts, seeds, and lean proteins is essential to support your body through perimenopause.
It’s also important to monitor your body’s response to fasting. If you notice negative symptoms like severe fatigue, dizziness, or irritability, you may need to reconsider your approach. You can adjust your fasting window or focus on the composition of your meals. Aligning your eating windows with your natural circadian rhythms can also optimize your metabolic function. Avoid eating late in the evening, as it can disrupt sleep and negatively affect how your body processes food.
Lastly, it’s important to consult healthcare professionals before starting any fasting routine, especially if you have underlying health conditions or take medications. Flexibility is key, and you should be prepared to adjust your fasting plan based on your health needs and lifestyle. If intermittent fasting causes too much stress or doesn’t provide the benefits you hoped for, it might be worth reconsidering its suitability for your overall health.
The Bottom Line:
Perimenopause can be a challenging time as your hormones shift and you experience changes in your cycle and symptoms. However, making simple lifestyle changes, like incorporating intermittent fasting, can help you manage this transition with grace. Fasting is not meant to be a grueling dietary regime or a punishment for gaining weight later in life. As Laura suggests, the best approach is to start small, listen to your body, and experiment to find what works for you. Combining intermittent fasting with healthy eating habits, such as following a Mediterranean diet, can provide a balanced way to achieve better health without a huge overhaul of your daily routine.
When it comes to managing perimenopause, intermittent fasting can be a transformative tool for balancing estrogen and progesterone, working with your body’s natural rhythms. It allows you to navigate this new phase of life while maintaining a sense of control over your health. If you’re struggling with these biological shifts, consider using available free resources like the Menopause Survival Guide or the 30-Day Ketobiotic Reset to support both your body and mind through this time.