Intermittent Fasting for Weight Loss

A Complete Guide for Women Over 40 (Perimenopause & Menopause)

There's tangible excitement about the power of fasting, and for good reason. Imagine what our neighborhoods would look like if we didn't have a trash day. Once a week, we set out our recycle bins, our trash bins and our green waste containers. The trash collection truck comes by and empties them all. What would happen if the trash collector stopped coming? We would become inundated with waste. Sure, with time, it would probably lead to more responsible consumption, more composting and less stuff. But in the short term, it would lead to a tremendous buildup of waste. There would be smelly, rotting trash all around us. It would eventually cause disease.

The same thing happens in our bodies if we don't find natural ways to get rid of our waste. We do have the regular methods of sweating and excretion, but that's not enough. This is where fasting comes in for a thorough trash collection.

The Science Behind Fasting: How Your Body Naturally Cleanses Itself

Fasting is one of the most healing tools we have. Our ancestors fasted regularly out of necessity because food was not always available. Our human biology has evolved to respond to fasting with a process of renewal. A break from food gives our bodies time to identify old cells, cancer cells and eliminate them. Water fasting cleans us out by detoxifying the liver. It gives all of the internal organs a rest from digesting food so that they can use their energy for cleanup and regeneration.

No longer do you have to eat the crappy airplane food to make it through your international flight. No longer do you become raving hangry when you miss breakfast. No longer are you persuaded by that less than desirable snack to get you through the workday. Fasting clears your head and gives you a superhero-kind of focus to get the job done.

How to Start Intermittent Fasting: A Beginner's Guide for Women

The key to fasting is to go slow and be mindful. Consider the fact that your body already knows how to do this. If you are sleeping, you are fasting. Your first meal of the day is called break-fast for a reason.

Begin by establishing a 12-hour feeding window, which simply means that if you eat breakfast at 7am, then you end dinner by 7pm and don't eat anything after. Over time, you may reduce your feeding window to 9-10 hours. By contrast, the majority of us are eating for 16 hours a day, making rest and digest difficult and a proper cleanup impossible.

Most of us can benefit from a 12-hour fast every day. Fasting for 12 hours everyday will improve your metabolic health, blood sugar regulation, enhance your longevity, and it doesn't cost anything! Who doesn't love trash day?

Nutrition Comes Before Fasting (Especially for Women Over 40)

Like all things in our information and trend-saturated world, we can easily take fasting to an extreme and harm ourselves in the process. Fasting is just one tool in your tool belt that should be considered within the context of a nutrient-dense diet.

Focus first and foremost on fueling your body with a rich and diverse diet to get all of the macros and micros for optimal nutrition and health. Only then, incorporate fasting.

After establishing that 12-hour daily fast, each person will have a unique set of health concerns, metabolism and hormonal balance that should be given careful consideration before experimenting with longer fasts. This is best done with the guidance of a doctor or health practitioner.

Hormones Matter

Women, especially during our reproductive years, need to be extra cautious with fasting since our hormones have different needs depending on where we are in our cycle. Furthermore, as we age, we need to prioritize maintaining lean muscle mass and bone health. Eating a protein-rich diet is a top priority, and therefore, most days, eating three protein-dense meals, starting with breakfast, is a good protocol against muscle loss.

If you are still cycling, you can bring in some fasting into the follicular phase of your menstrual cycle, the first 14-21 days. This is a good time to keep blood sugar low to support estrogen, and fasting can help. However, it is not advisable to fast during the luteal phase, the last 8-10 days before menstruation begins, when your body needs extra nourishment and extra complex carbohydrates to support progesterone.

An excellent resource about how to use fasting to support hormonal health is Fast Like a Girl by Dr. Mindy Pelz. 

Intermittent Fasting for Weight Loss: What Women Need to Know

Now let's talk about what you came here for: using intermittent fasting specifically for weight loss. Due to our unique biology, women don't lose weight as quickly as men through fasting. Women's bodies are designed to protect reproductive function, which means our hormonal systems are more sensitive to caloric restriction and fasting. This is why being mindful of your hormonal cycle is essential for weight loss success with intermittent fasting.

The Sweet Spot: The 15 Hour Fasting Window

For many women, intermittent fasting with a 15 hour fasting window during the follicular phase of your cycle can effectively support weight loss. This means eating your meals within an 9 hour window. For example, if you finish dinner at 6pm, you wouldn't eat again until 9 am the next morning. This extended fasting period allows your body to shift from burning glucose to burning stored fat, which is key for weight loss.

Weight Loss Resistance: The 36-Hour Fast

If you've been consistently doing shorter fasts and the scale isn't budging, you may be resistant to weight loss and could benefit from longer fasts of up to 36 hours. However, this is not something to do lightly or frequently. Extended fasts should only be attempted once or twice a month, always with the support of a medical provider, and strategically timed with your menstrual cycle.

The optimal timing for a 36-hour fast is during the follicular phase—either before ovulation or after ovulation but before the luteal phase begins. This timing works with your hormones rather than against them.

Exercise While Fasted for Faster Results

Exercising in a fasted state can accelerate weight loss by maximizing fat burning. When you work out before breaking your fast, your body has no choice but to tap into fat stores for energy. However, this strategy comes with one critical requirement: you must break your fast with adequate protein after your workout. Aim for at least 25-30 grams of protein to build and maintain lean muscle mass. Without sufficient protein, you risk losing muscle along with fat, which will slow your metabolism over time.

Open Your Detox Pathways

If your detox pathways are blocked, weight loss will stall. Consider that fasting mobilizes stored toxins in your fat cells. If your liver, gut, kidneys, lymphatic system, and skin aren't functioning optimally, those toxins have nowhere to go, and your body will resist releasing fat.

Support your detoxification with these daily practices:

Gut Health: Ensure daily bowel movements. If you're not eliminating waste every day, toxins are being reabsorbed. (See my post Menopause and Stomach Bloating for more details.)

Sweat Daily: Whether through exercise, sauna, or hot baths, sweating is one of your body's primary detox pathways.

Hydration: Drink plenty of filtered, mineral rich water throughout the day to support kidney function and toxin elimination.

Dry Brushing: This simple technique supports lymphatic drainage and helps move toxins out of tissues.

Castor Oil Packs: Apply castor oil packs over your liver at night to support liver detoxification while you sleep.

Lymphatic Drainage Massage: Regular massage or self-massage techniques help move stagnant lymph fluid and support detoxification.

When your detox pathways are open and flowing, your body can safely release stored fat, and weight loss becomes much easier.

Fasting is Your Birthright

Fasting is a powerful tool that can transform your metabolic health, mental clarity, and longevity. It's your biological birthright, hardwired into your DNA from thousands of years of human evolution. But like any powerful tool, it must be used wisely and within the proper context.

Start with a nutrient-dense diet and establish a simple 12-hour daily fast. Honor your unique hormonal needs, especially if you're a woman navigating perimenopause or the menopausal transition. Work with a qualified practitioner if you want to explore longer fasting protocols.

And remember: the temporary discomfort of fasting is an investment in your future health, clarity, and vitality. It's your body's natural trash day, and everyone deserves a clean house.

Frequently Asked Questions

Is intermittent fasting safe for women over 40?

Yes, when done properly. Women over 40 should start with a gentle 12-hour overnight fast and prioritize protein-rich meals (25-30 grams per meal) to preserve muscle mass. If you're still menstruating, fast during the follicular phase of your cycle and eat normally during the luteal phase. Always consult with a healthcare provider if you have underlying health conditions.

What's the best fasting schedule for weight loss during menopause?

A 12-15 hour daily fast works well for most menopausal women. For example, finish dinner by 6pm and don't eat again until 9am the next morning. This improves insulin sensitivity and supports fat burning while being sustainable long-term. Focus on eating three protein-dense and fiber rich meals during your eating window.

Can I drink coffee during my fasting window?

Yes, black coffee and plain tea are generally fine during your fasting window but it is wise to check for a glucose spike with either of these beverages. In addition, be sure to choose pesticide and mold free products. Avoid adding cream, milk, sugar, or butter, as these will trigger an insulin response and break your fast.

Will fasting make me lose muscle mass?

Not if you do it correctly. Daily intermittent fasting (12-15 hours) preserves muscle mass when combined with adequate protein intake. Aim for at least 25-30 grams of protein per meal, eat three meals during your eating window, and consider strength training to maintain lean muscle as you age.

What are signs that fasting isn't working for me?

Stop or modify your fasting if you experience increased anxiety, disrupted sleep, extreme hunger, hair loss, menstrual irregularities, constant fatigue, or worsening brain fog. These signs indicate that fasting is creating too much stress on your system. Return to three balanced meals per day and work with a practitioner to address any hormonal imbalances first.

How long does it take to see weight loss results from intermittent fasting?

Most women see initial results within 2-4 weeks of consistent fasting. However, results vary based on your starting point, overall diet quality, stress levels, detox pathways and hormonal balance. Remember that fasting is just one tool—nutrition quality, protein intake, and stress management are equally important for sustainable weight loss during perimenopause and menopause.

Ready to optimize your nutrition and discover what works for your unique body? My Nutritional Healing with Metabolic Balance program creates a personalized nutrition plan based on your blood chemistry, helping women navigate perimenopause and menopause with sustainable, results-driven strategies. Book a free call and tell me how I can support you.