Fasting has become increasingly popular in recent years, and for good reason. It’s been touted as a powerful tool for weight loss, improved metabolic health, and even longevity. But with so much information (and misinformation) out there, it can be confusing to know where to start, especially for women.
As a longevity coach, I’m passionate about helping women make informed choices about their bodies. Fasting can be a valuable tool, but it’s crucial to approach it safely and choose methods that align with your body’s needs.
Intermittent Fasting vs. Time-Restricted Eating
First things first, let’s clear up some common confusion. Intermittent fasting (IF) and time-restricted eating (TRE) are often used interchangeably, but they’re not quite the same thing.
Intermittent fasting is an umbrella term for various eating patterns that cycle between periods of eating and voluntary fasting on a regular schedule.
Time-restricted eating is where you eat all your meals within a specific window of time each day, typically 8-12 hours.
Common Fasting Methods for Women
Women’s bodies are unique, and certain fasting methods may be more suitable than others. Here are a few options that are generally considered safe (with conditions) for women:
Time-Restricted Eating (TRE)
This is a great starting point for most women. Begin with a 12-hour eating window (which to be honest should be called ‘normal eating’) and gradually reduce it to 8-10 hours as you feel comfortable. I would not recommend eating in a time window of less than 8 hours for the following reasons:
Stress Response: While some stress can be beneficial, excessive or chronic stress can negatively impact women’s health. For women, a very restricted eating window can contribute to increased stress (cortisol) levels.
Hormonal Fluctuations: Women’s bodies go through more hormonal shifts than men’s. These fluctuations can influence appetite, energy levels, and how we respond to fasting. A shorter eating window can disrupt this delicate balance.
Blood Sugar Regulation: Women tend to have different blood sugar responses compared to men. Severely restricting eating hours can sometimes make it harder to maintain stable blood sugar levels.
Nutrient Needs: Women have unique nutritional requirements, especially for iron and certain vitamins. When you condense your eating window, it can be more challenging to ensure you’re consuming all the essential nutrients your body needs to thrive.
5:2 Fasting
Eating normally for five days a week and restricting calories to 500-600 on two non-consecutive days. However, it is very important if you follow this fast that you do not exercise or do anything that requires lots of energy on your two fasting days. Two days a week on such low calories would not be easy to build into a busy lifestyle, especially for active women and therefore not one I would recommend.
Alternate-Day Fasting
Alternating between days of normal eating and days of complete fasting or very low-calorie intake. Not exercising on fasting days is again recommended and therefore you would be very limited in what you could do each week. This type of fasting would not be recommended for long term health and longevity.
Prolonged Fasting
Fasting for extended periods, typically 24 hours or longer. However, this type of fasting is too challenging on the female body for women due to our stress response, hormone fluctuations, blood sugar regulation and nutrient needs.
Fasting and Exercise
As women approach midlife, it’s crucial to prioritise fuelling our bodies properly, especially when exercising. Fasting around training times can be counterproductive, leading to decreased energy levels, impaired recovery, increased stress and a negative effect on our health and longevity.
Instead, focus on nourishing your body with the nutrients it needs to support your workouts and recovery. This means eating a balanced diet with plenty of protein, carbohydrates, and healthy fats.
According to Dr. Stacy Sims, (@drstacysims on Instagram), today’s leading expert on female-specific exercise and nutrition, women should aim to eat a small snack containing around 15 grams of protein before a workout (and 30 grams of carbohydrates if doing cardio), and prioritise consuming 45-60g protein within 30-45 minutes post-exercise to optimise recovery, with a focus on the higher protein intake for women in their reproductive years and perimenopause. This is different for men because they have a longer recovery window and so fuelling in a fed state is not as crucial during exercise.
Longevity Fasting & the Fasting Mimicking Diet (FMD)
I’m fascinated by recent research showing promising links between fasting and longevity. Studies suggest that fasting can activate cellular repair processes, improve insulin sensitivity, and reduce inflammation, all of which contribute to a longer and healthier lifespan.
There is one approach that stood out to me called the Fasting Mimicking Diet (FMD). This approach involves a specific eating plan that “tricks” your body into thinking it’s fasting, even though you’re consuming a small number of calories.
Research on the FMD:
Dr. Valter Longo (@prof_ValterLongo on Instagram) and his team at the University of Southern California have conducted extensive research on the FMD, with promising results.
Their studies have shown that the FMD can:
- Promotes cellular regeneration and repair
- Enhances stem cell production
- Reduces inflammation and oxidative stress
- Supports weight loss and metabolic health
- Improve cognitive function and protect against age-related diseases
You can find more information about their research here:
https://pmc.ncbi.nlm.nih.gov/articles/PMC10879164/
The Science Behind FMD:
It is a 5-day eating plan that aims to provide the benefits of fasting while still consuming some food. For maximum results it’s recommended you do the 5 day plan once a month for 3 consecutive months.
It is strategically chosen to trigger specific physiological responses associated with fasting, without requiring complete abstinence from food.
Why 5 Days?
- Long Enough for Benefits: This duration allows sufficient time for the body to experience the above effects.
- Short Enough for Adherence: It’s more manageable for people to stick with a 5-day plan compared to longer fasts.
- Minimises Risks: Prolonged fasting can lead to nutrient deficiencies and muscle loss. The FMD mitigates these risks.
Days 1-2:
- Metabolic Shift: The body starts transitioning from using glucose as its primary energy source to burning fat.
- Cellular Cleansing: Autophagy, a process of cellular renewal and recycling, begins to ramp up.
Days 3-5:
- Growth Hormone Increase: Levels of growth hormone surge, promoting cell repair and regeneration.
- Immune System Reset: The immune system undergoes a “rebooting” process, potentially leading to reduced inflammation.
- Stem Cell Production: The body may start producing new stem cells, which can differentiate into various cell types and contribute to tissue repair.
What Does FMD Look Like?
- Low-Calorie: The FMD restricts calories to about 1100 on day 1 and 750 on days 2-5.
- Strict Macronutrient Ratio: focuses on low protein, high good fats, and high healthy carbs.
- Whole Foods: plant-based foods like vegetables, fruits, nuts, and seeds.
- Hydration: drinking plenty of water, herbal tea, and clear broths.
The FMD is a fascinating area of research with the potential to revolutionise how we approach aging and longevity. And so I have decided ‘in the name of science’ to try it out myself!
I have never fasted in my life and it’s been decades since I severely restricted calories but the short length of this and the benefits means I’m willing to give it a try. And importantly, please note I will not be training during this time.
Look out for a future blog and social media posts to document how I got on!
In Conclusion
There are many considerations for women to make before they consider fasting. TRE is the safest form for women with no less than an 8 hour eating window. Other types of fasting, especially extended periods of fasting are not as good for us.
Whenever fasting or undertaking any severe calorie restriction:
- Listen to your body: Pay attention to hunger cues and adjust your fasting schedule as needed. If you ever start to feel unwell – stop!
- Stay hydrated: Drink plenty of water, herbal tea, and other non-calorie fluids during fasting periods.
- Prioritise nutrient-dense foods: When you do eat, focus on whole, unprocessed foods packed with vitamins, minerals, and antioxidants.
Disclaimer: The information provided in this blog post is for educational purposes only and should not be considered medical advice. Always consult your doctor before starting any new dietary or lifestyle changes.