Intermittent Fasting for PCOS: Is it Healthy?


Have you recently come across intermittent fasting and are now wondering if it can help your PCOS?

Living with PCOS and its symptoms can be a daily struggle. So I understand why you may want to give intermittent fasting a go.

Intermittent fasting is frequently talked about in the PCOS community. Many intermittent fasting advocates speak of the health benefits they have personally experienced. However, you may be asking yourself, will it work for me?

This post is an in-depth guide on intermittent fasting. We will look at what it is, the benefits and drawbacks and ultimately if intermittent fasting is healthy for PCOS.

Therefore if you want to find out whether to follow intermittent fasting for PCOS, you will love this guide.

What is Intermittent Fasting?

In recent years intermittent fasting has gained popularity. And one of the biggest misconceptions about intermittent fasting is that it is a fad. However, I can promise you this is not the case!

Intermittent fasting is a way to schedule your eating. The whole premise of it involves not eating for an extended period of time and then eating all your food in a short and specific time window. It, therefore, does not dictate what foods to eat but instead when to eat.

For example, as you will see below, one way to follow intermittent fasting is to fast for 16 hours and eat all of your food in an 8 hour time window.

For many people, this may sound bonkers as they are used to eating several meals throughout the day. However, Dr. Mattson, a senior investigator for the National Institute on Aging, states our current eating habits are abnormal. Dr. Mattson explains from an evolutionary perspective, our ancestors did not eat three meals a day including snacks. The need to eat every 3 hours or your body will go into "starvation mode" is a myth. Our bodies are able to survive long periods without food.


You might be wondering:

How do you do it?

As I said, intermittent fasting is about scheduling when you eat and when you don't eat. But with the increase in popularity, new intermittent fasting methods have been created.


Types of Intermittent Fasting

Below are the types of intermittent fasting methods you can choose from. When selecting the approach, you want to make sure it fits in with your lifestyle because you want it to be sustainable.

The 16/8 Method

The 16/8 method involves fasting for a maximum of 16 hours every day with an "eating window" of 8 hours. The "eating window" is the period you have to eat all your calories. You decide when your 16-hour fast begins.

For example

If your last meal is at 11 pm and you do not eat anything until 3 pm the next day, you have fasted for 16 hours.

During your fasting period you can drink water or any other non- caloric beverage to stop you from feeling hungry.

The 5:2 Fasting Diet

The 5:2 diet is simple. It involves eating normally for fives day and then lowering your calories to 500-600 2 days out of the week. The diet recommends women reduce their calories to 500.


Eat-Stop-Eat is more rigorous because it includes a 24 hour fast once or twice a week.

For example

If you finish your last meal of the day at 6 pm you cannot eat until after 6 pm the next day.

Some people may find fasting for 24 hours easier than reducing calories for a few days. You may find eating a small number of calories makes you feel even hungrier over not eating anything.

The Warrior Diet

Ori Hofmekler created The Warrior Diet, where you overeat one day and then the next day undereat. The diet was built on the premise of eating like an ancient warrior. Ancient warriors had little to eat during the day, and instead ate what they hunted at night. Hofmekler believes the warrior diet awakens the human survival instinct.

For 10 to 18 hours a day, you eat light snacks, such as raw fruits or vegetables or protein-based food such as yogurt. Hofmekler advocates exercising during the undereating period and eating one large meal at night.

Alternate-Day Fasting

Alternate-Day fasting involves fasting every other day. During days of fasting, food is not entirely restricted. It is recommended you eat 25 percent of your normal caloric intake.

For example, if your body requires 2,000 calories a day to lose weight, you would consume 500 calories on a fasting day. While on regular non-fasting days, you would eat 2,000 calories.

Spontaneous Meal Skipping

Spontaneous meal skipping is simple and can easily be followed. Skipping meals is something you may do intentionally and unintentionally. If you are not hungry, just don't eat anything, even if it's 'time' for a meal.

Skip Breakfast or Dinner?

Researchers found skipping either breakfast or dinner resulted in weight loss.

However, the results show subjects who skipped breakfast broke down more stored fat. And while this may seem like a huge benefit, it may not actually be as great as it sounds.

Researchers believe an impairment in metabolic flexibility may be developed. This is when the body is unable to switch between burning fat and carbohydrates for fuel when needed. The researchers reveal in the long term such a problem may cause inflammation and may harm blood sugar balance.

Scientists, therefore, warn against skipping breakfast due to the link between chronic inflammation, insulin resistance and the increased risk of Type 2 diabetes.

We have discussed the methods of intermittent fasting. Now let's identify the benefits and why it has become a popular approach in the treatment of PCOS.

Benefits of Intermittent Fasting for PCOS

Intermittent fasting has been studied at lengths and researchers have found tremendous health benefits to fasting.

Facilitates Weight Loss

One of the most talked about benefits of intermittent fasting is its ability to promote weight loss.
A common symptom of PCOS is weight gain or trouble losing weight. Dr. Mattson, explains "if you don't eat for 10–16 hours, your body will go to its
fat stores for energy, and fatty acids called ketones will be released into the bloodstream". Our bodies are smart, when it is low on energy, it will use our body fat for fuel.

Reduces insulin levels

Around 70% of women with PCOS suffer from insulin resistance. Researchers describe fasting as one of the quickest ways to increase insulin sensitivity.

What is Insulin and Insulin Resistance?

Insulin is a hormone released by the pancreas in response to spikes in blood sugar levels.

One of the main roles of insulin is to keep blood sugar levels under control. But how does insulin do that?

Think of insulin, like this:

When we eat a meal that contains carbohydrates our body will break it down into glucose and our blood sugar levels will rise. Due to the rise in blood sugar, our pancreases releases insulin. Insulin's job is to let that glucose into the cell of the body to be used as energy. It is for this reason insulin is often compared to a key because insulin unlocks the door for glucose to enter your muscles.

Insulin resistance is a condition in which the cells in the body no longer respond to the effects of insulin. Women with insulin resistant PCOS are not absorbing the sugar in the bloodstream. In turn, the pancreas secretes even more insulin to try and do the job. The sugar continues to build up in the blood and the high insulin levels lead to PCOS symptoms like infertility, irregular periods, weight gain.


So How Does Intermittent Fasting Help?

Fasting for 24-36 hours has been shown to help lower insulin levels because during the fasting period our blood sugar levels are normal and insulin isn't being produced. In addition, Dr. Fung, a world-leading expert on intermittent fasting, says a combination of both regular fasting and a decrease in insulin levels can significantly increase insulin sensitivity and treat insulin resistance.

In Practice:

Results from a study found intermittent fasting successfully reversed the insulin resistance of three insulin-dependent Type 2 diabetes patients. The outcome being discontinuing their insulin therapy. The case study clearly shows insulin resistance can be reversed naturally without the use of medication.

Improvement in such a huge PCOS risk factor may suggest that intermittent fasting is a healthy and effective treatment approach for PCOS.

Lowers the chance of Depression and Anxiety

Women with PCOS are at greater risk for anxiety and depression. But research shows intermittent fasting can help.

A 2001 study found three months of intermittent fasting, in which the individuals fasted every other day, notably increased brain-derived neurotrophic factor (BDNF) in the hippocampal. Research suggests low BDNF may be linked to depression, anxiety and neurodegenerative disease, such as Alzheimer's.

More recently, however, researchers found within a week of intermittent fasting participants reported an improvement in their mood. The participants explained how they felt more alert and had a sense of tranquillity. However, further research on intermittent fasting and mood is needed to assess whether the improvement in mental health persists for the long term.

Reduces Stress Levels

A clinical trial studied 40 PCOS women. Participants were equally divided into 2 groups, the study group: those who fasted and the control group: those who did not fast. Researchers found fasting resulted in a huge decrease in cortisol, the primary stress hormone.

Therefore, if you suffer from long term stress, fasting may be a great way to lower cortisol levels and help your PCOS.

Reduces LDL Cholesterol

Research shows 70% of women with PCOS have high levels of LDL cholesterol, 'bad cholesterol', and low levels of HDL cholesterol, 'good cholesterol'. Both of which are associated with cardiovascular disease.

A study found participants who followed intermittent fasting for 8 weeks decreased LDL by 25%.

Simply put...

All of the above benefits are incredible. The results show fat loss, improvements in insulin resistance and depression, as well as a decrease in LDL cholesterol. Such results are highly encouraging for women with PCOS.

But, there are some drawbacks.

Drawbacks of Intermittent Fasting for PCOS

Below are the cons of intermittent fasting based on current research and information from experts.

Risk of Insulin Resistance

In contrast to the results discussed above in the benefits section, the findings from a more recent study show intermittent fasting may not be effective for insulin resistance. Researchers studied healthy adult rats subjected to intermittent fasting which involved no food every other day, for three months. The team recorded a decrease in overall body weight, however, they found an increase in abdominal fat tissue. So despite weight loss, the rats showed more fat on their abdomen which may be a sign of insulin resistance.

In addition, the researchers found damage in the cells of the pancreas which release insulin. As well as markers of insulin resistance and increased levels of free radicals.

Now whilst this is a more recent study we have to bare in mind it is an animal study, so results on humans may vary, but it does signify that women looking to use intermittent fasting as a way to treat their insulin resistance and PCOS should be cautious. Remember to always pay close attention to the feedback that your body is giving you when trying any new way of eating.

Increases Cortisol Levels

While researchers found intermittent fasting to be effective for lowering cortisol. Many Doctors recommend individuals suffering from Hypothalamic-Pituitary-Adrenal (HPA) Axis Dysfunction should avoid intermittent fasting. Experts indicate fasting is a stressor on the body and therefore following intermittent fasting may increase cortisol levels.


So, if you suffer from any of these symptoms don't follow intermittent fasting as it may not be healthy or safe:

  • Difficulty waking up in the morning
  • High energy levels in the evening
  • Cravings for salty food
  • Difficulty managing stress
  • Anxiety

Loss of menstrual cycle

Female sex hormones are sensitive to energy intake. Women must take extra care when lowering their food intake to prevent any negative effects.
Precision Nutrition explains how the gonadotropin-releasing hormone (GnRH), released by the hypothalamus is responsible for the release of luteinizing hormone (LH) and follicular stimulating hormone (FSH) from the anterior pituitary.

LH and FSH then trigger the production of the female sex hormones estrogen and progesterone. Women require both hormones during ovulation to release a mature egg. Sudden changes in energy intake, for example, through following Intermittent fasting can throw off GnRH pulses.

The effect of stress on your period

Altering your food intake in any way, e.g. eating less food, creates a negative energy balance which your body perceives as a stressor. Our bodies cannot distinguish between a real imminent threat and you simply trying to lose weight.
Cortisol, the primary stress hormone, prevents GnRH from carrying out its role and stops the production of estrogen and progesterone.

Precision Nutrition highlights during periods of stress, progesterone is converted to cortisol resulting in less progesterone and even more cortisol. Not enough progesterone leads to estrogen dominance which can cause even more problems.

You might be wondering:

Well, what's the big deal if I miss my period?

Here's the deal:

You might be saying to yourself I am not currently looking to get pregnant so why does it matter if I don't see a period. Sure, females menstruate for the sole purpose of bearing children. But, there are more reasons why you need a menstrual cycle. Including:

  • bone health
  • energy
  • better moods
  • libido

So while everything may seem fine and dandy in the short term, in the long term you will notice huge changes in how you feel and function overall.

But also, women with PCOS already suffer from irregular periods and therefore following intermittent fasting may not be healthy for PCOS.

Eating Disorders

Eating disorders are prevalent in women with PCOS and many advocates of intermittent fasting, perhaps unintentionally, promote methods of fasting which encourage extreme behaviors. Many portray intermittent fasting as a way to eat whatever and however much you want during your eating window.

Most proponents of intermittent fasting recommend eating nothing for a period of time but then eating healthily and sensibly. However on an occasion, for example, once a week, to let yourself indulge in ‘unhealthy foods.'

Following rules and restrictions around fasting may create, or aggravate an existing eating disorder.

Your hunger cues aren't the enemy

Constantly suppressing your body's hunger cues can make you think feeling hungry is wrong. However, feeling hungry is not the enemy, your body gives you these cues because it needs fuel.

If you are someone who has an existing eating disorder or you have recovered from one, intermittent fasting may not be healthy for you.


Need for further research

The increase in popularity of intermittent fasting led to the creation of various fasting diets. It is therefore not clear which method is best and more effective, alternate day fasting, 5:2 diet, 16/8 method.
Further research must be done to assess whether intermittent fasting is healthy for PCOS and if it is something people can adhere to in the long term.

So what does this all mean?

Should You Follow Intermittent Fasting?

So the question remains, is intermittent fasting healthy for women with PCOS? The evidence clearly shows intermittent fasting has huge benefits for your overall health, including weight loss, lower levels of stress, inflammation, and LDL cholesterol, as well as a better mood. However, the jury is still out on whether intermittent fasting is healthy and safe for women with PCOS.

Unfortunately, there isn't a straight forward answer. Firstly because there is still conflicting results among research. Studies are not concurrent on whether intermittent fasting is suitable for the treatment of insulin resistance.

Remember we are all different

What works for one person doesn't mean it will work for you. Before embarking on any new approach, you must be aware of your current hormonal state to avoid causing further problems to your health. So if you suffer from adrenal PCOS or fatigue intermittent fasting may not be healthy or safe.

Lastly, intermittent fasting is not a quick fix to a problem. Improvements in your health can take time, therefore be patient and consistent.

Proceed with Caution

Here is what you must do if you decide to follow intermittent fasting for PCOS. Pay close attention to how you are feeling. Stop following it if you experience symptoms such as low energy, loss of menstrual cycle, trouble falling asleep.

Remember female hormones are sensitive to changes in energy intake. Pay attention to what phase you are in your menstrual cycle.

Best way to fast during your menstrual cycle

I spoke about how fasting is a stressor on the body and how during periods of stress our progesterone levels decrease which can lead to elevated estrogen. Therefore taking this into consideration, to make intermittent fasting healthy for PCOS, avoid fasting for longer than 12 hours during your menstrual phase. During this phase of your cycle, you want estrogen levels to decrease to prevent symptoms of high estrogen-like heavy bleeding and headaches.

The follicular phase of your cycle is when our body is better able to tolerate fasting. This is because both estrogen and progesterone naturally rise during this phase. As a result, an increase in estrogen caused by fasting will not have an effect on the bodies natural hormone spike.

Also, avoid fasting beyond 12 hours during the ovulation and luteal phase of your cycle. This phase of your cycle is where your body is trying hard to protect the egg which may potentially become a fetus if implantation occurs. During this phase, your body is trying to store energy for the potential baby. Therefore make sure you are eating enough food because if you are not you will notice increased hunger and irritability.

Personal Experience

Personally, I do not follow a strict form of intermittent fasting. I much prefer eating according to my 'body clock'. This means I eat when I am hungry. However, I do believe in its benefits and with that said, I follow intermittent fasting in a way that is healthy for my PCOS.

I aim to fast for at least 12 hours. But during phases of my cycle which allow longer fasting, I fast for 13-16 hours. Any longer than that I start to feel tired, weak and moody.

Here is an example of my eating schedule:

I have my final meal at 7 pm and I break my fast around 7-9am. I do not eat breakfast as soon as I wake up because I have more clarity and focus during those fasting hours. Further benefits I have noticed include, I sleep better and wake up feeling well rested.

Lastly, I much prefer eating my final meal around at 7 pm the latest because I like giving my body enough time to digest the meal before I go to sleep (at around 10:30).

Bottom Line

If you don't suffer from an eating disorder, HPA Axis Dysfunction or lost your period, intermittent fasting may be a safe and healthy approach to follow for your PCOS. But always consult a medical professional before you change your diet. And remember, listen to your body!


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Hey there! I am Despina Pavlou, founder of PCOS Oracle, certified personal trainer and corrective exercise specialist.  I want to share with you the diet and lifestyle changes I made to naturally reverse my PCOS and achieve hormonal balance. I believe using my holistic approach you too can take back control from PCOS.


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  1. Casey on June 13, 2019 at 2:54 am

    Do you have any info on how to do intermittent fasting while on metformin? Thank you!

    • Despina on June 14, 2019 at 3:04 pm

      Hey Casey!
      It is often recommended to take metformin with food, as some people have experienced nausea when taken on an empty stomach (during the fasting period). While others have noticed no issues. However, it is best to discuss this with your Doctor. You can also work with your Doctor on establishing the progress achieved following Intermittent Fasting on your insulin resistance to finally figure out when you can eventually come off metformin.

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