The topic of intermittent Fasting for women is extremely confusing. For women, implementing intermittent fasting requires some special considerations to ensure it’s done safely and effectively. If done correctly, intermittent fasting can have huge benefit to overall health, digestion and hormone balance. To note, there is still not enough research on intermittent fasting for reproductive aged women specifically, but based on the little information we have, here are some simple rules that women can apply.
1.Always Have Breakfast:While the idea of fasting might suggest skipping breakfast, it’s crucial for women to break their fast in the morning to support their hormonal balance, mood concentration and energy levels. Skipping breakfast may lead to an increase in the hormone cortisol and inflammatory markers in the body which can disrupt the normal functioning of the menstrual cycle and can lead to a delay in ovulation.
2. Allow 4-6 Hours Between Meals with No Snacks:
Intermittent fasting is all about giving your digestive system a break. To reap the full benefits, it’s essential to allow a significant gap between meals, ideally 4-6 hours, without snacking. This approach helps maintain steady insulin levels and encourages the body to tap into fat stores for energy.
3.Maintain a 12-14 Hour Overnight Fast:
The overnight fasting window is one of the cornerstones of intermittent fasting for women. Aim to maintain a fasting period of 12-14 hours between dinner and breakfast. This practice helps regulate insulin sensitivity, improves digestion, and promotes restorative sleep. Many women have heard that intermittent fasting is bad for women’s hormones, but this unfortunately has lead to some wrong assumptions about what that means. Some degree of fasting is necessary, especially overnight, in fact maintaining a 12 hour fast can actually help reduce cortisol and promote a calm nervous system which is needed for hormone balance on the whole. Fasting for too long has the opposite effect, where cortisol is released to help stabilise blood sugar. Each woman is different and has a different tolerance to fasting, but in general most women do best with keeping an overnight fast of 12-14 hours all month long. I have not seen any research on longer fasts of 24 – 48 hours etc for women. These are unlikely to be beneficial for women unless only done rarely (once or twice a year), but this is just my opinion based on what I can deduce from the information available.
4.Longer Fasting Windows in the Evening, Not the Morning:
For women, fasting in the morning can disrupt hormone balance and lead to potential hormonal irregularities. Instead, extend the fasting window in the evening when the body is naturally winding down. This approach aligns with the circadian rhythm and minimises hormonal disruption. This follows a restricted eating approach which emphasises the need to align the body with its natural rhythms for best health outcomes. It also emphasises the importance of not eating late at night and allowing a minimum of three hours before bedtime without food. This helps support digestion, metabolism and sleep.
5.Consider Extended Fasting in the Follicular Phase if Insulin Resistant or Have High Androgens:
Some women with insulin resistance, PCOS or high androgens may benefit from an extended fasting window of up to 16 hours during the follicular phase of their menstrual cycle. However, based on the studies, improvements in hormones with longer fasts were still during the extended evening fast and not the morning. Breakfast is still important.
6.Stay Hydrated:
Water intake is important during intermittent fasting. Hydration helps curb hunger pangs, supports detoxification, and aids overall bodily functions. Make sure to drink plenty of water throughout the fasting and eating windows to stay hydrated.
7.Nourish Your Body with Whole Foods:
During the eating window, focus on consuming nutrient-dense whole foods. Opt for a blood sugar friendly balanced diet rich in fruits, vegetables, proteins, and healthy fats. Avoid processed foods and excessive sugar, which can disrupt the benefits of intermittent fasting.
8.Exercise in a fed state:
Women respond better when exercising in a fed state. While many women believe that exercising fasted can help them achieve weight loss faster, the practice of exercising in a fasted state only raises cortisol higher which can then causes disruptions to hormone balance and may actually lead to weight gain over time. Exercising after meals is also supportive of blood sugar balance and helps to flatten the blood sugar curve. Plan workouts within an hour of having a meal. High-intensity workouts and intense exercise might require adjustments to the fasting schedule because more calories are needed. Consult with a professional if needed.
9.Adjust Calorie Needs to the Menstrual Cycle:
Women’s calorie needs can fluctuate throughout the menstrual cycle due to hormonal changes. Most reproductive aged women need around 2000 a day calories, less in the follicular phase and more in the luteal phase. Up to 300 calories extra are needed in the luteal phase. During the follicular phase (the first half of the cycle), estrogen makes the body more insulin sensitive and suppresses appetite. Less food and lighter foods can be eaten in this phase. The body is also more tolerant to carbohydrates during this phase and blood sugar is naturally more stable. You can experiment with slightly longer evening fasts during the late menstrual phase and follicular phase, especially if you have elevated androgens. Ideally still keep the fast 12-14 hours with an absolute max of 16 hours if you have PCOS, are overweight or have insulin resistance. In the second half of the cycle, progesterone leads the body towards insulin resistance and appetite increases. More calories are needed in the second half of the cycle and an emphasis on balancing meals adequately with enough protein, carbs and fats is important. Extended fasting in the follicular phase can lead to increase in PMS symptoms, period pain and blood sugar imbalances.
10.Prioritise Sleep:
Adequate sleep is crucial for overall health, especially when practicing intermittent fasting. Ensure you get 7-9 hours of quality sleep each night to support hormonal balance, mood, and cognitive function. Sleep has a more profound effect on blood sugar and weight than fasting. If intermittent fasting is interfering with sleep, then its best to prioritise sleep over fasting.
11.Listen to Your Body: Intermittent fasting is not a one-size-fits-all approach. Each woman’s body is unique and may respond differently to fasting. Pay attention to your body’s signals and adjust your fasting window accordingly. If you feel excessively fatigued or experience hormonal irregularities, consider modifying your fasting schedule.
Intermittent fasting for women is a dynamic process that requires attentiveness and flexibility, especially as a woman. Listening to your body, honouring your menstrual cycle, and making adjustments when necessary will lead to a more sustainable and beneficial fasting experience.
If you would like a more in depth view on many of the points discussed in this article you can read more of my articles on this topic:
https://talidavoinea.au/intermittent-fasting-vs-time-restricted-eating-for-women/
https://talidavoinea.au/the-downfalls-to-snacking-for-blood-sugar/
https://talidavoinea.au/how-to-fast-with-the-menstrual-cycle/
https://talidavoinea.au/the-importance-of-breakfast-for-women/
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