Is Intermittent Fasting Good For Acne?

Is Intermittent Fasting Good For Acne?

Intermittent fasting is a pattern of eating that cycles between periods of not eating (fasting) and eating. It has gained popularity among the paleo/primal community as a way to ‘hack your body’, and it’s touted to have almost miraculous health benefits.

In this post I want to talk about intermittent fasting for acne. We’ll go over things like: Can it help? Can it be harmful? Who should and who should not try it? And how to do it?

Is IF natural for humans? The thrifty genotype hypothesis

From evolutionary perspective modern life is highly unnatural. For the vast, vast majority of existence humans lived as hunter-gatherers. It’s unlikely that prey animals volunteered to walk into human tribes and donated their bodies for food, nor did the fruits, berries and root vegetables pick themselves up and made their way into our ancestors’ cook pots.  All this is to say that getting food required physical activity, either as hunting or gathering.

Sometimes food was plentiful, sometimes it was scarce. Sometimes the hunt was successful, other times not. Our ancestors lived through periods of when they had plenty to eat and through times when they had very little to eat.

Some scientists suggest people with ‘thrifty genes’ were the best adapted to survive these periods of feast and famine. Thrifty genes are defined as ‘being exceptionally efficient in the intake and/or utilization of food’. In other words, people who stored the most food as fat and were the most effective at utilizing those fat storages were the most likely to survive. And we are descendants of ancestors with the thriftiest genes; genes that have barely changed during the past 10’000 years.

Many of the current chronic health problems could be a consequence of conflict between ‘Space Age’ circumstances and ‘Stone Age’ genes. Conflict between 24/7 food availability and sedentary lifestyle and genes that evolved for cycles of feast and famine and activity and rest.

Intermittent fasting tries to emulate the natural feast-famine cycles of our ancestors.

Can it help you to get clear? Let’s see what the science has to say about this.

Studies on the benefits of intermittent fasting

Animal studies consistently show that intermittent fasting:

  • Improves insulin sensitivity and reduces insulin levels
  • Reduced systemic inflammation
  • Improves cholesterol levels
  • Increases animal’s stress tolerance – cells exposed to chemicals take less damage
  • Increases lifespan and results in overall improvements in health

Unfortunately the data on humans is far less convincing, partially because relatively few human studies have been done, and those studies often raise more questions than they provide answers.

Possible improvements in insulin resistance

Most human studies on intermittent fasting show improvements in insulin resistance – though caveats apply.

Helibronn et al put 8 men and 8 women on 22-day alternate day fasting regimen, meaning they had to fast every other day but could eat as much as they wanted on the other days. This graph shows insulin and blood sugar levels at baseline, morning after eating day (day 21) and morning after fasting day (day 22).

Effect of intermittent fasting on blood glucose and insulin

Source: Alternate-day fasting in nonobese subjects: effects on body weight,  body composition, and energy metabolism.

As you can see, insulin levels dropped dramatically after fasting days, but were slightly higher after eating days. I should say that both the baseline and the eating day (day 21) reading were taken after 12 hour fast. The participants were allowed to eat until 7pm and the measurements were taken 7am the next morning.

In another study by Helibronn et al. they again put 8 men and 8 women on 22-day alternate day fasting regimen. At the beginning of the study men had quite a bit higher insulin levels than women. After the study insulin levels dropped in men but increased in women, indicating alternate day fasting reduced insulin resistance in men but increased it in women.

Halberg et al. asked 8 young men to fast for 20 hours every other day for 14 days. Compared to the baseline measurements, the participants showed less insulin resistance and lower insulin level.

Harvie et al. put 107 overweight or obese women on 25% energy restricted diet for 6 months. The participants were randomized to either continuous energy restriction (CER) or intermittent energy restriction (IER). The CER was like normal diet. The IER group could eat normally on 5 days per week, but had to eat very little on 2 days per week. So it’s sort of modified IF.

Both groups lost the same amount of weight and had comparable improvements in sex hormone and inflammation levels, but insulin dropped more in the IER group.

There are also a few other studies that put overweight/obese people on IF regimen. All of those studies showed improvements in insulin resistance and blood lipids. But they lacked a continuously caloric restricted people as control group, so we can’t say if the benefits are due to caloric restriction or fasting.

IF may to downregulate mTor pathway

Soerter, et al. studied the effect of 2-week IF regimen in 8 healthy, non-insulin resistant men. They had the participants fast every second day for 20 hours for two weeks, after which they were switched to normal diet for 2 weeks. Diets during both periods had the same amount of calories and were calculated to maintain weight.

Under these conditions there were no changes in blood sugar or insulin levels, but mTor activation was lower during the IF period. mTor is sort of a master regulator in acne and increased activation of the mTor pathway leads to more acne.

Increases stress tolerance

IF may improve stress tolerance. Animal studies show that animals kept on IF regimens are more resistant to negative effects of stress. Human studies show similar results. Cells from people doing IF show higher resistance to oxidative stress, such as dangerous chemicals.

Science summary

Small number and bad quality of the available studies makes it hard to say what effects, if any IF, has on humans. However, most studies show improvements in insulin resistance and blood sugar control, both of these would be good for acne, as would be the reduction in mTor pathway activation.

With so little data at hand there is obviously still a lot we don’t know. The vast majority of these studies used alternate day fasting, and it’s hard to say how well the benefits (and harms) translate to shorter 14 – 20 hours fasts. Most of these studies were short, only 2 to 3 weeks. It’s possible that you need more time to really see the results.

Can IF be harmful?

Paradoxically, prolonger fasting (72 hours and more) can cause insulin resistance, this may also happen during prolonger IF.

One study in rats showed that 8-months of intermittent fasting increased insulin resistance, but rats kept on normal caloric restriction diet didn’t experience such deterioration. Caloric intake was equal in both groups, so it looks like the negative effect was due to IF.

It’s likely that fasting, or famine, state puts stress on the body. Like exercise, this is useful in moderation, but fasting too much or too long can put too much stress on your body.

Intermittent fasting may be harmful for women

While there’s no good human data available, animal data shows that males and females react differently to caloric restriction/starvation. One study showed that caloric restriction slows down or completely shuts down reproduction in female rats and caused endocrine masculinization (balance of sex hormone shifted towards androgens – bad for acne). Anecdotal human experiences suggest that exercising too much or restricting calories is bad for some thin women with PCOS.

Fasting can also make you irritable and tired. Studies show traffic accidents peak during Ramadan in Muslim countries. Fasting can also reduce alertness and concentration.

From my own fasting experiments, I can say that I start to experience problems focusing and become irritable when my fast goes beyond 18 hours. The few times I tried to fast by skipping dinner and breakfast turned out as complete disasters as concentration problems made it very hard to work those mornings. Nowadays, when I fast, I fast from lunch (2 to 3 PM) until breakfast (8 or 9 AM).

Should you try IF for acne?

IF is not for everyone and should be considered as an advanced technique, especially considering that studies show only moderate benefits on acne risk factors and in some cases may even worsen them.

You may benefit from intermittent fasting if:

  • You are overweight
  • You are insulin resistant
  • You are a woman with PCOS or other androgen-related problems and you are above normal weight
  • You get acne from sugar or milk

In case any of the following apply, I wouldn’t try IF:

  • You are thin/underweight, especially women
  • You already eat a very restricted diet
  • You are highly stressed
  • You don’t sleep enough has a good article on problems IF can cause for women. If you are a woman and consider IF, I highly recommend you read Stefani’s article first.

How to do it?

Fasting is rather simple. Just don’t eat or drink anything with calories for a certain period of time, and there’s no need to complicate it further.

I like to think of intermittent fasting as ‘compressed eating window’. Let’s say you normally have your breakfast at 8pm and your last bite to eat at 8pm, so you have 12 hour eating window, and, consequently, fast 12 hours per day. During IF you would shorten, or compress, eating window to say 6 or 8 hours and would fast the rest of the day.

I recommend fasting between 14 and 20 hours. 14 hours is probably the minimum amount required for body to switch to primarily burning fat and for insulin level to really drop. On the other hand, fasts that go beyond 20 hours start to cause irritability and fatigue, making them difficult to stick to. Though if you are fat-adapted, that is your body burns mostly fat and you are on low-carb diet, then long fasts are probably easier to deal with.

Long fasts can also cause unwanted weight loss. All the human studies on alternate day fasting showed that the participants couldn’t eat enough during eating days to compensate for lack of calories during fasting days.

Feel free to position your eating window anywhere you want on the clock. Many people recommend fasting from 6pm to noon or 2pm the next day. As I mentioned, skipping breakfast is problematic for me and that’s why I fast from 2 to 3pm until 8 to 9am.

Try to avoid anything containing calories during fasting time, but feel free to drink coffee, tea, water and other non-caloric beverages.

For more details, I recommend you check out The Beginner’s Guide to Intermittent Fasting at


Intermittent fasting is an interesting technique for fitting our Stone Age genes into modern day life. IF may lower insulin level and mTor activation and thus be helpful in acne.

That said, while it theoretically makes perfect sense and has compelling support from animal data, I would consider it as an advanced technique. Something you can play with and see if it works for you. But until we get more compelling evidence from human studies, I wouldn’t recommend it for ‘general consumption’.

Have you tried intermittent fasting? How did it work for you? Care to share tips with other readers? Use the comments below.

About Me

Hi, I am Acne Einstein(a.k.a. Seppo Puusa). I'm a bit of a science nerd who is also passionate about health. I enjoy digging through medical journals for acne treatment gems I can share here. You can read more about my journey through acne and how I eventually ended up creating this.

30 thoughts on “Is Intermittent Fasting Good For Acne?”

  1. Seppo,
    before my acneiform diagnosis [you can guess who I am!] – when I had acne – I used the intermittent fasting method after I needed to fast for a blood test [once a week for several weeks in a row]. At first I found it hard then not so hard. so I went to intermittent [every other day] fasting. For me it had little more effect than cutting my carb intake to less than 10g a day. I was already on a less than 10g carbs a day strict regime. I monitored my blood sugar and it was the same as the less than 10g. So, I couldn’t see the point of continuing intermittent fasting and gave up. I only tried for a matter of weeks mind. And I was going 24 hrs without eating.

    I might well retry this but not eat after 3pm just to see any effect on acneiform. For the record, although I know acneiform is different, I just increased my carb/sugar intake the week before last to eating whatever I like [chocolate biscuits, bread!!!!] for the first time in years and years. Result? Worst breakout I’ve had in years. Nasty. Still trying to get it under control.

    • Hi there again!

      Thanks for sharing your experience. Looking at the data, sparse as it is, I wouldn’t expect intermittent fasting to have much effect over going low carb. But there’s still not enough data to say for sure. It’s possible that long-term IF could have better effect.

  2. Hey Sep, thank you for finally bringing up the article! I have to admit most of it did I already know but I was interested in finding out what you thought about IF.

    As for me.. I went on a training regimen a while back like 4-5 months ago when my acne was most severe but I was following an alt-med routine to keep my acne in check.. In any case the training program wanted me to IF 16 hours daily. and my memory is kinda hazy from there. I’m not entirely sure if it did much to my acne.. I remember a period where the state of my skin kinda felt like it was.. frozen like nothing would happen. It neither progressed towards clear skin but it didn’t really end up in the part of the scale where I get acne.. I’m not entirely sure if it was because of IF but it may have helped a bit since I wasn’t using any form for face washes or moisturizing creams with antioxidants. Nor taking antioxidant supplements.. So it may have benefited me a bit. Who knows.

    Any hows, I’ll go on IF again next week since I’m going to be training again, then I’ll see if it’ll help. 🙂

    I think I found some pages talking about how IF decreases IGF-1? Anything you found out about?

    • Based on my preliminary look at the studies I actually expected IF to have much bigger effect, especially considering how it’s hyped in the paleo and health circles. So I was quite surprised that the studies showed so small effect. But I wouldn’t close my mind on IF yet since the human studies are still fairly weak and inconclusive. There’s strong and consistent evidence in animal studies for IF, so it’s possible we need longer studies, and perhaps the alternate day fasting is too much.

      Anyway, based on what we’ve talked before, I remember you saying your acne is more linked to stress. So perhaps IF is not the right thing for you?

      One study did shower somewhat higher IGF-1 in the IF group. But the other papers didn’t make any mention of that, so don’t know if that was just a study artefact or whether it’s a real effect. I do know that growth hormone levels increase significantly during a fast, so perhaps it’s linked to that.

      • Well I suspect my acne being linked to stress and the levels of acne severity goes up and down without me doing anything special to my diet etc etc.. The only thing I can think of is my mood and it’s something that I never really take note of, I don’t even realise I’m stressing out myself until an hour or so later while doing whatever I do that stresses me out. + I do have some negative emotions I need to work on so that’s also that..

        Regarding IGF-1 levels, I can ask a friend of mine.. Well the same fitness trainer about a study of IGF-1 levels regarding IF, maybe he can fish one up like he did with simple carbs not affecting blood sugar too much.

  3. just want to add 2 things:

    1. i found the IF to be mentally, at time, a challenge but, at other times, quite uplifting. A mind over matter type experience.
    2. When you come off it don’t whatever you do go straight back to your normal eating regime. I had my normal breakfast of bacon and eggs and felt bloated and v nauseous and had to lie down. Ease yourself back in with small easy to digest meal.

    • I’ve also noticed that fasting is occasionally tiring but at times very energising and puts me into a very productive state.

      Not sure about your second point. 16 to 20 hour fast is still quite short and not sure there’s need to ease yourself off from it. At least I’ve never experienced any problems eating after a short fast.

  4. There is also a recent study that shows that women with PCOS have greatly lowered insulin and testosterone levels by eating most of their calories at breakfast and small meals for lunch and dinner. This may be important to keep in mind if one is considering doing intermittent fasting.

  5. I can’t relate to any of the positive effects of IF but I’m a woman weighing 52 kg. Sometimes skipping meals doesn’t affect me too much but I feel awful before having breakfast and I can’t concentrate when I’m hungry. I can’t sleep if I didn’t have enough for dinner. Also, it’s the worst thing to shop when I’m hungry – it’s so difficult to resist all the junk food! And it’s so tempting to eat something sweet. And for some reason it becomes easier to gain belly fat or maybe it’s just bloating? I don’t know, however, IF is not for everyone.

  6. I was intermittent fasting today, and when I was fasting and I reached her 16th-17th hour and my skin was actually less oily! My nose wasn’t oily anymore and my forehead was less oilier. And it can really be oily sometimes!

    So yeah, I’m going to experiment with this a bit more.

          • But Sep, I think you should do a blog post on why it’s ”okay” to have acne as in.. It’s okay to still get a pimple even though you do ”everything” correctly. Something that we talked about over mail where I came to terms with my feelings. I actually got a pimple today on one of my temple.. It’s VERY faint. But I’m trying to not let it run out of hand because that will only make things worse. And acknowledging those facts has actually me a bit.. I think that’s why my skin didn’t break out for a week or two during my break.. well other than not being stressed so much!

            A blog post on how to reduce acne marks would be amazing as well!

  7. Hi Seppo, I do hope you read this comment as you seem to be the only one who can answer it.

    Basically, somewhere last year I began IF where I was originally supposed to fast 2 times a week for 24 hours. However, as I got used to it there were times where I would just fast the whole day and pig out at night. I would do this 5 times a week and eat normally for the remaining two days a week. I did this for a few months and started breaking out with cystic acne. It got so bad that I had to be put on antibiotics. However on that diet I did lose alot of weight. Right now, I’m looking to lose weight again and I’m currently on a low carb diet but I find it too difficult to maintain and would prefer going back to IF.

    My question is, do you think the reason I broke out is because of my erratic eating pattern of fasting and eating whenever I wanted? Maybe the hormones in my body started fluctuating too much? Also, Do you think I would have the same issue if I followed the IF plan as it was laid out originally where I only fast twice a week for 24 hours? Thank you for your time and this article man.

    • Thanks for your comment Simon. I’m afraid I’m not an expert on IF so I can’t give you a good answer. I can say that fasting puts a lot of stress on the body, and fasting too much can have detrimental effects. As far as I understand, long term IF can increase cortisol levels, which can lead to blood sugar and hormonal issues. Apparently, it can also mess up circadian rhythms. While there’s no research to confirm this, I suspect that both of those could aggravate acne.

      If you haven’t already, I suggest you put this question to Paul over at

  8. hi Seppo, thank you for the fast reply, really appreciate it. Yes I will send this question to Paul as well I’m really hoping to get back into IF soon. Cheers

    • If you want to continue with IF, perhaps try limiting fasting time to 16 hours a day. That should put less stress on your body.

  9. Intermittent fasting has done wonders for my skin, so I went online to see if it was just in my head or if others have had similar experiences and this is the first page that popped up, so even though it’s a little old I thought I’d share my experiences in case other people find this page with a similar search as well.
    I track both my diet and my acne with an app and last night I was thinking about how I haven’t had acne in about four months, and then I realized that is exactly how long I have been 5:2 intermittent fasting. I go 15 hours initially between dinner and the next day’s lunch, and then another 4-6 hours until dinner, then it’s another 15 hours till breakfast the next day. Total caloric intake during that time is 500 very low-carb/high fat calories. I do this on Mondays and Thursdays. I haven’t lost very much weight, though my boyfriend has, but we were both normal weights to begin with. I have PCOS and am a 31 year old female.
    I have had acne since the moment I hit puberty, and in the past approximately 18 years of having it I have been on numerous medications and nothing helped more than it hurt. I’ve never had clear skin for such an extended period of time, especially while totally cutting out medicated products (even benzoyl peroxide and salicylic acid). IF has also improved my day-to-day energy levels, which were previously very low. I tend to look forward to my fasting days. I think it’s worth a try after educating yourself well about how to do it healthfully if you have lifelong acne like I do.
    Feel free to ask me questions.

  10. ..i think i will try fasting for a few days and eat soup with a few potatoes in the afternoon…i hope that it will not cause insulin resistance ….:/
    good informations …. naimi

  11. thanx for the article , my experience with fasting to treat acne ,is positive one… I think fasting (with other things added),to be the fastest effective treatment of acne ….
    the first step I took is to fast ,nothing gets into my mouth , after 12 at least 12 hours ,I drank lemon juice without sugar , and salad conists of huge amounts of tomatoes,carrots,parcely , cabbage,brocoli,onion,cucumber…. and olive oil ….

    then fruit as papaya or whatever ..
    then rice with grilled chicken …

    also I applied several things as bynzol piroxide and others ..but nothing was as fastly effective as combination of erythromycin + zinc ..

    after few works as magic…

    yes fasting reduces acne , I know my body well… it reduce the inflamation of the acne ,and makes the treatment faster….

  12. I have been researching acne and any relationship it may have to the ketogenic diet. Your website was an absolute gem to find and I can’t believe I have never come across it until now. Attempting to single out why it has been quite bad lately is a nightmare. Perhaps the big “M” being a 54 year old woman or the sweetener in diet drinks. Who knows but it is a shock as I have good skin normally. Any insight?

  13. Whilst MTor does get down regulated a little bit with 18 to 24 hour fasts, it really only starts shutting down after 60 to 72 hours. At 72+ hours, my acne tends to disappear almost all together, and my BG (which is normally around 100), is down around the mid to low 60’s mg/dl.

    What also happens after 72+ hours is something called autophagy, which is a process of your body going around scavenging broken cells and pieces of cells (subcellular). After a week long fast (168 hours), I noticed that a non-cancerous tumor I’d had on my right elbow had strunk a bit. After another two week long fast, it had totally disappeared. It also tends to clean up scarring a bit.

    The last fast I did was a week long (ended it last Wed), and I broke it with two BLT’s (on flax bread), and a large bowl of chicken noodle soup (used shirataki noodles), and finished with a few sugar free mounds bars I had made earlier that week, and I think I had some cheese later too. Yes, I do a strict ketogenic diet…. Two days later it was “revenge of the zits”, especially on my back. Between the protein in the bacon, the chicken soup, the cheese, and then the damned chocolate, it really did a number on me. I’m still sporting a water zit on my forehead.

    In the past, when I’ve broken a week long fast with a totally plant based meal like a flax, chia, and shredded coconut cereal in almond milk (and no chocolate), I do not recall having that much of a acne reaction to eating again.

    I’m going to carefully log what I eat, and my acne reaction, the next time I break a long fast, and see what works and what doesn’t. I’m thinking plant based food, and as much omega 3 to omega 6 oils as possible to tamp down the inflammation reaction.

    Thanks for the insight on the MTor/protein/acne connection. After my recent zit fest from a “not so clean” (nitrates in the bacon, cheese, chocolate, ect) keto refeed, it makes sense why I had that breakout.

    Of course the usual “homeopathic” advice I got was “toxins”,which made no sense (if it is the “toxins” that are coming out of the fat, then why no zits during the fast?).

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