I was listening to a podcast the other day when a scientist posed a question that made me sit up — well, almost, considering I was out walking and narrowly avoiding getting tripped up as my dog ran in front of me to chase a squirrel. But I digress… He asked why, in a study of participants undertaking a 30-day fast, there were no women included. The response from the other scientists? “The female data varies too much. It’s easier to just study men because their variables are more steady.”
As a woman, a fasting practitioner, and someone who has spent years understanding the science and nuance of health and healing, I was both unsurprised and deeply frustrated. Once again, women were being excluded from research simply because we are biologically different. But that very difference is what makes understanding how women should fast so incredibly important.
The female body is not a small male body
For decades, most medical, nutritional, and fitness research has been conducted primarily on men, with findings then generalised to women. But the reality is that our hormones, metabolism, and biological rhythms differ vastly from men’s. Men operate on a relatively straightforward 24-hour hormonal cycle, with testosterone peaking in the morning and gradually declining throughout the day. Women, however, cycle over approximately 28 days, with fluctuating levels of oestrogen, progesterone, and even testosterone at different phases of our cycle.
Testosterone, often thought of as a “male hormone,” is actually essential for women too. It supports muscle growth, libido, and cognitive function. We produce most of our testosterone in the first half of our cycle, particularly around ovulation. However, because our hormones shift so significantly throughout the month, we need to align our lifestyle — including fasting and eating patterns — to support these natural changes rather than work against them.
The four phases of the female cycle: the seasons of womanhood
To truly optimise fasting, we must look at the four phases of our menstrual cycle: menstruation, the follicular phase, ovulation, and the luteal phase. These phases mirror the seasons of the year, each with its own energy, needs, and ideal fasting approach.
Winter: menstruation (Days 1–5)
Just like winter, menstruation is a time for rest, reflection, and conservation of energy. Oestrogen and progesterone are at their lowest, leaving many women feeling tired, introspective, and craving warmth and nourishment.
Fasting approach: Gentle fasting, if any. A 12-hour fast (from dinner to breakfast) can be beneficial, but extended fasts, unless practiced, may add unnecessary stress to the body. Focus on warming, iron-rich foods such as stews, soups, and leafy greens to replenish blood loss and support recovery.
During this phase, women often feel more withdrawn and prefer solitude or smaller, more intimate gatherings. It’s a time for introspection, journaling, and engaging in gentle movement like stretching or walking. Just as animals conserve energy in winter, we, too, benefit from allowing ourselves to slow down. Pushing through with intense exercise or prolonged fasting can lead to fatigue and increased stress.
Spring: follicular phase (Days 6–14)
As oestrogen rises, energy increases, much like the fresh bloom of spring. This is a time of growth, motivation, and heightened metabolism.
Fasting approach: This is the best time for longer fasts, such as 16:8 or even occasional 24-hour fasts. Insulin sensitivity is at its peak, making the body more efficient at burning fat. Pair fasting with strength training to maximise muscle building and metabolic function.
This is the time when women tend to feel their most outgoing and adventurous. Social events, networking, and new experiences feel exciting rather than overwhelming. Just as nature bursts into life in spring, women feel a natural inclination to take on new projects and challenges. This is the phase where fasting feels effortless, workouts feel invigorating, and productivity is at its peak. Taking advantage of this hormonal window can lead to remarkable physical and mental gains.
Summer: ovulation (Days 14–18)
Ovulation is the peak of our cycle — our internal summer. Oestrogen and testosterone are at their highest, making us feel social, confident, and strong.
Fasting approach: Moderate fasting, such as 14–16 hours, is still effective, but the focus should be on balanced nutrition to support high energy levels. Prioritise protein for muscle repair and recovery, and ensure adequate hydration.
During this phase, women often feel their most magnetic and attractive. This is an excellent time for social engagements, big presentations, and relationship-building. Just like summer, this is when we feel our most vibrant and alive. However, over-fasting at this stage can lead to increased cravings or metabolic stress, so balance is key. Supporting the body with ample nutrients ensures optimal hormone function.
Autumn: luteal phase (Days 19–28)
As progesterone rises and oestrogen declines, our energy begins to wane. Like autumn, this is a time for slowing down, turning inward, and preparing for the next cycle.
Fasting approach: Extended fasting is not ideal in this phase. Instead, opt for shorter fasting windows (12–14 hours) and focus on nourishing, grounding foods such as root vegetables, healthy fats, and magnesium-rich foods to support progesterone production. Listen to your body — if hunger increases, honour it.
Women often feel more sensitive and less tolerant of stress during this phase. Like the trees shedding their leaves in autumn, we may feel the urge to let go of things that no longer serve us. It’s a good time for reflection, home-based activities, and reducing external pressures. Many women experience heightened cravings in this phase, which is the body’s way of preparing for potential pregnancy. Instead of resisting, focus on nutrient-dense foods to keep blood sugar balanced and mood stable.
The science of female fat storage
Women naturally store fat differently than men due to oestrogen and progesterone. We tend to hold fat around the midsection, hips, and thighs, which serves as an energy reserve for pregnancy and breastfeeding. This biological difference is why calorie restriction and fasting must be approached strategically for women, as excessive fasting can lead to stress responses that encourage the body to hold on to fat rather than burn it.
Scientific insight: Studies show that women’s fat cells have more alpha-2 adrenergic receptors (the ones responsible for storing fat) than men’s, especially around the abdomen. This means that stress, poor nutrition, or over-fasting can actually trigger fat storage in these areas, counteracting the fat-burning benefits of fasting. (Source: International Journal of Obesity, 2004). Therefore, it’s crucial for women to tailor fasting protocols to their unique needs.
A client’s story: from resistance to thriving
One of my clients was adamant that fasting was not for her. She had tried intermittent fasting before and found that it left her feeling exhausted, irritable, and with worsening PMS symptoms. She had read countless articles stating that fasting was beneficial but felt that it simply didn’t work for her, so she gave up.
After discussing her hormonal cycle and other considerations, we tailored a fasting approach specific to her needs. Instead of fasting rigidly every day, we adjusted her fasting schedule based on her cycle, with longer fasts in the follicular phase and shorter eating windows in the luteal phase. Within two months, she noticed profound changes: better energy levels, improved mood, reduced bloating, and a more regular menstrual cycle. By working with her biology rather than against it, she unlocked the benefits of fasting in a way that felt sustainable and nourishing.
My client’s transformation was a testament to the power of aligning fasting with the female cycle. Her body began to function in harmony with its natural rhythms, and she felt empowered by the changes she was experiencing.
Practical takeaways: tracking your cycle for fasting alignment
To start incorporating fasting with your unique cycle, tracking your menstrual phases is a great first step. By doing this, you can optimise your fasting schedule according to your body’s hormonal fluctuations.
- Track your cycle: Use a period tracker app or a simple calendar to note the start of your period, ovulation, and other symptoms. This will help you predict the phases ahead.
- Adjust fasting windows: During the follicular and ovulatory phases, try incorporating longer fasts (16–18 hours) and strength-based workouts. During the luteal and menstruation phases, focus on shorter fasts (12–14 hours) and nutrient-dense, grounding meals.
- Listen to your body: If you’re feeling extra hungry or fatigued during certain phases, that’s your body’s way of signalling what it needs. Honour those signals, and don’t be afraid to adjust your fasting window.
By syncing fasting with your cycle, you can optimise your energy, fat loss, muscle gain, and hormonal balance.
Who should avoid fasting?
While fasting offers incredible benefits, it is not suitable for everyone. Pregnant and breastfeeding women should avoid prolonged fasting, as their bodies require a steady supply of nutrients to support both their own health and that of their baby. Women with a history of disordered eating should also be cautious, as fasting can sometimes trigger restrictive behaviours.
The takeaway: women are not men, and that’s a good thing
For too long, women have been expected to fit into male-dominated health models. But we were not designed to function like men. Our cyclical nature is not a flaw — it is our power. When we stop trying to fit into a “man’s world” and start honouring our unique biology, we thrive.
Fasting is a powerful tool for women, but it must be approached with awareness, mindfulness, and respect for our natural cycles. When applied incorrectly or as a one-size-fits-all approach, it can have adverse effects and get a bad name. But when done right — tailored to the unique rhythms of the female body — it can be a game-changer for our health and well-being.
By embracing our natural fluctuations, we can use fasting not as a rigid protocol but as a fluid and supportive tool to help us thrive.