Is Intermittent Fasting Healthy For PCOS?

Intermittent fasting has been a hot topic in the PCOS community. Women with PCOS are known to struggle with their weight, gaining pounds very easily and experiencing difficulty losing it. Many are fed up and desperate with their efforts to control their weight with no success. It’s tempting to see other women on social media posting their before and after pictures from fasting and wonder if you should give it a go.

Fasting, which has been around for centuries, is known to cause weight loss (not eating can do that) and is associated with longevity. But is fasting really that healthy for women with PCOS and does it really work? Here’s what the evidence shows and what we have to say about it.

What Is Intermittent Fasting?

Intermittent fasting is voluntarily withholding of food (and sometimes beverages) for a set period of time. There are several types of intermittent fasting including complete or alternate-day fasting, modified fasting, time-restricted fasting, and religious fasting.

Complete or alternative-day fasting

This type of fasting alternates between several days of no food at all followed by a regular diet the rest of the week.

Modified fasting

Modified fasting restricts the amount of food eaten to 20% to 25% of total calories for two or more nonconsecutive days, followed by a standard diet the rest of the week.

Time-restricted fasting

This type of fasting involves eating as much as you want during specific windows, followed by fasting with set hours. For example, going 12 hours without food and only eating lunch for the day or no eating in the evening after 7pm through the overnight hours. This is the type of fast associated with fasting overnight for blood work.

Religious fasting

Fasting for religious or spiritual reasons, such as Ramadan for example.

How Does Intermittent Fasting Benefit Health?

There are several theories of how intermittent fasting can benefit health. One theory is cell rejuvenation. As cells are starved of energy, they begin to die, creating the regeneration of newer and healthier cells.

Another theory has to do with circadian rhythm. Our circadian clock plays a major role in metabolism, blood pressure regulation, and hormone secretion. Our bodies have evolved to depend on food during the day when it’s active, and not at night when it’s sleeping. Disrupting this clock by eating late at night could possibly increase risk of type 2 diabetes and other metabolic health complications. Evidence to support this is shown by night shift workers who have a higher risk of diabetes, obesity and cancer rates. Individuals who consume the majority of the day’s energy earlier in the day are associated with lower weight and improved health.

Intermittent fasting may have a direct effect on gut function. Several functions of the GI track are driven by the circadian rhythm. Glucose regulation and blood flow are increased during the day, and gastric emptying slowed during the night. Disrupting this rhythm could impair metabolism and health.

Is Intermittent Fasting Healthy for PCOS?

The short answer: no. The reality is, any type of fasting or caloric restriction will result in weight loss. If not done sensibly, fasting can be dangerous to your health and emotional well-being. Here are just some reasons intermittent fasting isn’t great for PCOS.

Lack of long-term results

Currently there is insufficient data to support the notion that fasting (in any form) can affect cardiovascular risk markers (i.e., blood pressure and blood lipid levels) or insulin and glucose to a greater extent than that seen with chronic dieting. Moreover, changes in HbA1c or insulin sensitivity levels beyond weight loss have not been established. A study published in Nutrients involving nine intermittent fasting studies lasting 6 months or more, failed to show any benefit of fasting over calorie restriction.

What is unknown, are the health benefits and risks of intermittent fasting in the long-term. Meaning, for individuals who engage in different types of intermittent fasting, what happens to their weight and health after 1 year, 5 years, and 10 years after stopping the fast? We know that when people diet and restrict their calories that they tend to regain the lost weight in the long-term. My guess is the same will hold true to fasting.

Focus isn’t on nutrition

With fasting, more emphasis is given to total calories eaten rather than how good the diet quality is. On non-fasting days, this may give a green light mentality to eat whatever, often times not so healthy foods, which can result in excess calories and defeating the purpose of the fast.

Contributes to blood sugar crashes and cravings

Intermittent fasting can contribute to increased hunger. Not helpful if you’re trying to shed pounds. Women with PCOS who have high levels of insulin are at risk for having low blood sugar episodes. Signs of low blood sugar include dizziness, confusion, sweating, headaches, and hunger. When blood sugar is low, carbohydrates are needed to raise levels. This is when cravings and binge eating results. If you’ve ever been hungry, you know what I mean. Without sufficient carbohydrates and food, blood sugar can become low, resulting in the symptoms mentioned or worse: you could pass out.

Poor emotional well-being   

Another factor unknown with intermittent fasting in adults is what impact will it have on one’s emotional well-being? Dieting is known to cause people to develop an unhealthy relationship with food and their bodies. Dieting also interferes with physiological cues of hunger and fullness. Ever been hungry and out of points? Too bad according to diets. Fasting is most likely going to do the same.

Anyone with an eating disorder (past or present) should not try intermittent fasting.

The One Good Time to Fast

The only time we advocate for fasting is at night when you’re not hungry. If you find yourself night-eating or regularly snacking while watching TV after dinner and you know you’re not hungry, your body doesn’t need the energy.

To experiment with the circadian rhythm theory, try to avoid eating late at night if you’re not hungry until breakfast in the morning. Go ahead and eat a satisfying dinner and call it a night. See if it makes a difference in your weight or how you feel. Let us know what you experience.


Weight-Loss Outcomes: A Systematic Review and Meta-Analysis of Intermittent Energy Restriction Trials Lasting a Minimum of 6 Months. Nutrients. 2016 Jun 8;8(6).

Patterson R. Intermittent Fasting and Human Metabolic Health. J Acad Nutr Diet. 2015;115(8):1203-1212.

C S Davis. Intermittent energy restriction and weight loss: a systematic review. European Journal of Clinical Nutrition (2016) 70, 292–299.

Seimon RV. Do intermittent diets provide physiological benefits over continuous diets for weight loss? A systematic review of clinical trials. Mol Cell Endocrinol. 2015;153-72.

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Comments (8)
  • Bri

    August 9, 2017 at 1:48 pm

    So you say absolutely no to intermittent fasting despite research saying it could possibly have beneficial results? The research is going both ways so I wouldn’t rule it out completely. Especially since you were fine with promoting essential oils with far less research supporting their use.

    Asemi, Z., Samimi, M., Taghizadeh, M., & Esmaillzadeh, A. (2015). Effects of Ramadan Fasting on Glucose Homeostasis, Lipid Profiles, Inflammation and Oxidative Stress in Women with Polycystic Ovary Syndrome in Kashan, Iran. Archives of Iranian Medicine (AIM), 18(12).

    Chiofalo, B., Laganà, A. S., Palmara, V., Granese, R., Corrado, G., Mancini, E., & Triolo, O. (2017). Fasting as possible complementary approach for polycystic ovary syndrome: Hope or hype?. Medical Hypotheses, 105, 1-3.

  • Angela Grassi

    August 10, 2017 at 9:45 am

    We aren’t saying it doesn’t work. You could try it out, at least overnight to see if it helps you. Let us know!

  • Naj

    November 27, 2017 at 11:28 am

    I have had nothing but positive results with intermittent fasting as a PCOS sufferer. I find that it does not actually cause “blood sugar crashes and cravings” as you highlighted. Rather, the effects were opposite. My blood sugar levels were great. I was able to come off Metformin. My period was regulated and started coming each month like clockwork. Even though I did not add much exercise except to incorporate more walking in my day to day activities; I lost weight and gained muscles mass; i.e. my body became lean. Energy levels soared. Acne disappeared. Hair started growing in thicker. Hirsutism was not gone, but regrowth of whatever hair which was removed was significantly slower; among other things.

    I also greatly disagree with the statement that the focus isn’t on nutrition. That is dependent on the individual. I would alternately fast for 24 hrs for 3 days/week. During my eating period, I would eat healthy carbs, lean protein, nuts and lots of green (and a small sweet snack because I have a dangerous sweet tooth). I also drank about 2-2.5 litres of water throughout the day.

    You can still fuel your body with healthy foods while fasting. And I strongly believe our bodies were not designed to constantly be in a fed state. There is plenty of research to support this. I think it’s worth looking into more.

  • shen womack

    March 25, 2018 at 9:30 pm

    I disagree. My personal results with fasting have been amazing! I NO longer have sugar crashes, mood swings, joint swelling, uncontrollable hand twitches, shortness of breath, high blood pressure, stomach acne, or multiple chins. I’ve lost 40lbs and feel great.

  • Ashley

    April 14, 2018 at 12:46 pm

    I don’t think that you are perceiving this as a lifestyle and looking at it as a diet. I fast for 18 to 22 hours a day with a six to two hour window of eating. Loading up on good fats, proteins and an indulgance here and there. It’s not meant to be a diet. We do the clean fast (water, black coffee, plain tea) during fast, with the target of reaching a ketogenic state and autophagy. It’s also improving my relationship with food, giving me appetite correction and has started to increase my craving for healthy options over processed. Weight loss is just one of the benefits. And those that are doing this for health reasons plan to incorporate IF for life. Once you reach health and weight goals, you can open your window for longer eating and maintenance. There are extreme versions of IF, but I follow the Delay, Don’t Deny by Gin Stephens. Very supportive group on Facebook moderated by her. I’m almost a month in and it has been the easiest way to lose weight, feel good and not deprived that I have experienced in 25 years of dieting.

  • Christina

    April 16, 2018 at 2:08 pm

    I have to disagree here… I’ve suffered long enough from pcos to know that my body is finally healthier and healing. My emotional as well as physical well being has improved dramatically! I have been fasting, lean gains (16/8), for a while now and my blood pressure has normalized, my sugar levels stay stable all day, cravings are gone and have lost fat around my neck and mid section considerably. Also, I don’t get pelvic pain like I used to, and my periods have actually regulated. I’m amazed that this article is so negative to I.F., as there are so many out there that have been able to heal their bodies of the negative symptoms of PCOS with it.

  • Angela Grassi

    April 17, 2018 at 9:42 am

    Christina, That’s great to hear that intermittent fasting has helped you. Can you share with us how you do it? Overnight fast versus daily fasts?

    We recognize that all women are different and respond differently. We don’t recommend intermittent fasting due to the lack of research and that the majority of women with PCOS struggle with binge eating.

  • Jen

    May 11, 2018 at 9:25 am

    Ok, so what I understood from this article is that there is no real evidence that intermittent fasting is bad for women with PCOS but rather that the danger of the jojo-effect is. I think that people should stop seeing IF as a diet but much rather as a lifestyle change.
    I personally have been fasting intermittently (500 calories twice a week) and I find that this is the best thing I have ever done. I’m eating a lot healthier, I am much more conscious about what I eat, and I am loosing weight. Once I have reached my ideal weight I plan to dial it back and only do one fasting day per week to maintain the weight. I think this is very sustainable in the long run. All it takes is a bit of will power 🙂

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