Reviewed by

Morgane Leten - Nutrition & Fertility Coach

  • Energy
  • Hormones
  • Nutrition

The Woman’s Guide to Intermittent Fasting

By now, you probably know someone who does intermittent fasting, or maybe you have tried it yourself. And why not? The countless articles and influencers praising this diet trend may have you believing that intermittent fasting for women can help with everything from weight loss to brain power.

For many people, intermittent fasting can be beneficial but for women considering giving this trend a go, you need to proceed with caution! 

If you’re not in tune with your body, fasting for prolonged periods of time may be largely ineffective, or worse, they can actually do more harm than good.

First, let’s get our facts straight…

What is intermittent fasting?

Intermittent fasting is simply going for short or medium periods of time without food. Simple, right? That’s why it’s been so popular. No fancy diets to follow or complicated recipes to make. Just stop eating!

The “not eating” window can vary in length. Some are as short as 12 hours and include sleep time. Some are as long as 16, 20 or 24 hours.

There are also different ways to fast. Some people do it everyday, others do longer fasts a few times per week.

This trend is hot right now, not just because it’s easy to do, but because the possible benefits are extensive and very appealing. Weight loss is an obvious benefit, but studies also show that fasting can help lower cholesterol, reduce sugar cravings, improve blood pressure, improve sleep and concentration.  Some people even report increased endurance and athletic performance.

Other Health Benefits

A number of human and animal studies suggest that the benefits of intermittent fasting may be quite varied:

Reduced inflammation: Some studies show that intermittent fasting can reduce inflammation. Chronic inflammation can lead to weight gain and various health problems.

Improved psychological well-being: One study found that eight weeks of intermittent fasting decreased depression and binge eating while improving body image in obese adults.

Increased longevity: Despite the fact that it has not been proven in humans yet, intermittent fasting has been shown to extend lifespan in rats and mice by 33–83%. Some food for thought… 

Preserve muscle mass: Intermittent fasting appears to be more effective at retaining muscle mass compared to continuous calorie restriction. Higher muscle mass helps you burn more calories, even at rest.

The health benefits of intermittent fasting for women need to be studied more extensively in well-designed human studies before any firm conclusions can be drawn but the evidence is certainly compelling. 

Intermittent fasting for women may help them lose weight and reduce their risk of heart disease and diabetes. However, more studies on humans are needed to confirm these findings.

Does intermittent fasting work for women?

Ladies, listen up. That list of benefits above may sound appealing, but if you don’t understand what you’re doing, fasting can actually do the opposite of what you want!

Whether motherhuud is on the horizon or not, a woman’s body is naturally built for reproduction. When you don’t eat for extended periods of time, your body thinks it's starving and it goes into “protect and preserve” mode. This mode is about survival! Your body will actually hang on to weight (in the event you needed to say, survive a famine!) and it increases your hunger hormones signalling to your brain to go get some food ASAP!

It also slows down things like your fertility, so you don’t waste energy on non-essential things like growing a baby.

If you’re not interested in having a baby, this might not sound like a big deal, but when you mess with reproduction, you mess with hormones. And, when your hormones are out of balance, you set yourself up for a whole range of health problems which are very likely the polar opposite of what you are trying to achieve with fasting.

Woman beware: Possible side effects of intermittent fasting

An intermittent fasting diet for women can affect the hypothalamus or the part of the brain that regulates hormones like estrogen. This hormone plays a critical role in your monthly cycle. When this happens, you could notice:

  • Low energy
  • Sugar cravings
  • Weight gain
  • Trouble concentrating
  • Dull hair and skin
  • Fertility challenges

Fasting can also disrupt cortisol production. When this happens, you might notice:

  • Increased anxiety
  • Low energy and brain fog
  • Inability to sleep

What about fasting and exercise?

If you’re adding a regular exercise routine on top of intermittent fasting, it’s good to know the potential risks. Fasting tells your body it is deficient in nutrients and often, when you add on the stress of exercise, it can cause your cortisol levels to skyrocket.

If you keep increasing your stress through exercise without fuelling your body properly, you will constantly be in survival mode and this can mess with your menstrual cycle.  You may even start storing more belly fat!

Instead of the weight loss and super powered brain you were hoping for, intermittent fasting may actually cause disrupted periods, higher anxiety, worse athletic performance and often, weight gain – the absolute opposite of what you’re looking for!

As you can see, intermittent fasting can have many benefits, but the potential negative side effects may be enough to scare you away!

How to fast safely if you’re a woman

The big question is: are there still ways to get the benefits of intermittent fasting if you’re a woman?

The answer is YES!

But you need to be smart about it.

There’s a few guidelines you can follow to ensure you reduce the risks and just get the guud stuff that fasting has to offer.

Here’s the best intermittent fasting schedule for women:

  • Don’t fast when you’re on your period. Your body is already working hard here so take care of it with nourishing food.
  • Tempting though it may be, don’t fast on consecutive days. Instead, pick one-two days per week.
  • Opt for shorter fasts of approximately 12 hours. Going any longer can start a hormonal crash.
  • Plan workouts according to your fasting days. Do your intense workouts on days that you are not fasting.
  • When you are eating, make sure you eat according to your cycle. What does that mean? Our blog post on How to Hack Your Cycle with Food will tell you all you need to know.
  • Try to time your fasts for the week after your period. During this phase, known as the follicular phase, your metabolism slows down meaning you’ll feel less hungry than other weeks. Your body actually needs more calories the week before your period so just be aware of these different phases when you plan your fasting days.

The key is to listen to your body. If the shorter fasts work well for you, consider increasing the length of time. But if you start noticing symptoms of hormonal imbalance, stop immediately!

Stop fasting if…

  • Your period becomes irregular or stops
  • You’re a zombie and can’t sleep
  • You feel off. Think: brain fog, grumpiness and general anxiety
  • Your hair and skin looks noticeably worse
  • You’re gaining weight
  • You have or are currently struggling with an eating disorder

The bottom line is that intermittent fasting effects men and women differently. So when you read about all the magical benefits, it’s good to keep in mind that there’s no one-size-fits-all approach.

Remember: the best diet is the one you can stick to long term. Find one that works for you and your lifestyle and stop immediately if you’re trying to conceive, pregnant or notice any of the warning signs.

Fasting FAQ

Here are answers to the most common questions about intermittent fasting.

Can I Drink Liquids During a Fast?

Yes. Water, coffee, tea and other non-caloric beverages are fine. It is best to drink your coffee or tea without cream, milk or sugar. 

Coffee can be particularly beneficial during a fast, as it can blunt hunger.

Isn’t it unhealthy to skip breakfast?

No. The challenge is that most people who routinely skip breakfast often have unhealthy lifestyles. If you make sure to eat healthy food for the remainder of the day after your fasting window, then the practice is perfectly healthy.

Can I take supplements while fasting?

Yes. We encourage it! But remember that some fat-soluble vitamins may work better when taken with food. 

Does fasting cause muscle loss?

Anything that causes you to lose weight can cause muscle loss, which is why it’s important to lift weights and keep your protein intake high. A 2011 study showed that intermittent fasting causes less muscle loss than regular calorie restriction.

Will fasting slow down my metabolism?

No. Some studies show that short-term fasts actually boost metabolism.

Want more advice on fasting? Get in touch with one of our experts.

We’d love to help!
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