Are You Eating Enough to Get a Period?

Keto period or amenorrheaLost your period? You might just need to eat more. A lot more. Losing your period to under-eating is called hypothalamic amenorrhea and is common, especially in women under thirty.

Hypothalamic amenorrhea is sometimes misdiagnosed as polycystic ovary syndrome (PCOS) because both hypothalamic amenorrhea and PCOS can present with “polycystic ovaries” on a pelvic ultrasound exam.

3 signs of hypothalamic amenorrhea

If your missing period is due to undereating, you will have one or more of the following:

  • no withdrawal bleed from the pill or a progestin-challenge
  • low fasting insulin (less than 4 mIU/L or 25 pmol/L)
  • low luteinizing hormone (LH).

You could also have polycystic ovaries (or not). Read Is it PCOS or hypothalamic amenorrhea?

How undereating stops periods

Too few calories or too little of any macronutrient (including carbohydrate) can switch off the signalling of the hypothalamus to the ovaries. It’s not a malfunction but is instead the brain making the smart decision to avoid pregnancy when there is not enough food to make a baby. It’s also called relative energy deficiency which is the ratio between energy intake, body mass, and energy expenditure (exercise).

Think of hypothalamic amenorrhea as an ovulation “off switch.”

Mechanism of hypothalamic amenorrhea.
Mechanism of hypothalamic amenorrhea.

Men do not have a similar “off switch” because although the male hypothalamus can dial testosterone up and down, it would never turn testosterone off completely. Why? Because a male hypothalamus never has to worry whether there will be access to the 75,000 additional calories it takes to grow a baby.

Ovulation can be switched back on simply by consuming more food in the form of (on average) a daily intake of 2500 total calories including 200 grams of starch. With increased calories and starch, the period should return within six months. It takes that long because of the “100 days to ovulation” I describe in Period Repair Manual.

👉 Tip: Hormonal birth control is not an effective treatment for hypothalamic amenorrhea because pill-bleeds are not periods.

Ovarian set point

But what about that friend who did a keto diet and did not lose her period? Hypothalamic amenorrhea is more likely to occur in some women compared to others which may depend on ancestry. Evolutionary biologist Grazyna Jasienska explains in her book Fragile Wisdom that different women have a different “ovarian set points,” by which she means the ability to ovulate given a particular availability of food energy.

Energy is the key to understanding ovarian function. ~ Dr. Grazyna Jasienska

Read Have you lost your period to a low-carb or keto diet?

Do you have an eating disorder?

If you’re frightened by the idea of eating more, please consider whether you have an eating disorder. Approach it with self-love and self-forgiveness, and know you’re not alone. Eating disorders are common and nothing to be ashamed of.

Reach out for help.

Dr Lara Briden

77 thoughts on “Are You Eating Enough to Get a Period?”

  1. I’m trying to figure out why I haven’t gotten my period since they took out my iud I was only 32, now I’m 44 and I’d love to have my 2nd child with my fiance but im not sure I can. I’m still having symptoms of a period but nothing comes. I have symptoms of pregnancy every month but nothing. We are trying to get pregnant but not sure what else to do since my period stopped. I tried progesterone pills 100mg,and a 1mg estrogen patch I had a period for 3 weeks then nothing since, I was on the medication for 6 months tve doctor at the time did nothing to help me understand why so I dumped her,and im left trying to figure out what to do. Someone please assist me.

  2. Hi! What counts as starch? Do carbohydrates from fruits and vegetables count? Do we need 200g of carbs total per day from all sources or specifically 200g of carbs from grains/potatoes?

  3. Hi Lara, i’m 17 and have had many go arounds with unhealthy eating patterns. My period has been gone for 3 or 4 months now. I dont know what to do, but i cant imagine eating three meals a day.. i dont know what to do. I feel like im never skinny enough, and when i was healthy i was fat.

    • Hi Ashley, i’d encourage you to open up to a medical professional – preferably an eating disorder specialist. Restrictive eating can wreck havoc on the body and overtime can increase your set point weight. The only way to fix this is to eat sufficient calories. And you’ll need more than you think for a brief period of time to counter the damage that restriction has done. Here is another great book on fixing periods:

      Aside from that look into who/what you are surrounding yourself with to make you focus on your weight (versus the other gifts/skills that you have!). Maybe stop social media for a while? Find friends that encourage/support you 🙂

  4. hi lara,
    i’ve not had a regular i have not had a regular period for ten years since my twins were born. i am a personal trainer/marathon runner. i do eat at a deficit 317 days a year. the only time i’ve had a period at all during this time was following an ischemic stroke caused by a tear in my right carotid artery in which i was forced to eat what the hospital fed me. i also gained about 15lbs during that time. i have since worked that weight off and again lost my period. i just turned 40 years old and do not plan to have any more children. did i already go trough menopause? my obgyn says he is not worried about the loss of my period as it is common with merena. please advise.

  5. My daughter has what we thought was thin PCOS due to polycystic ovaries and irregular periods. (Every 45-58 days) She was a state champion sprinter and after she stopped running track she got paranoid of weight gain and the horrible things PCOS can cause. She does HIIT exercise for 45 minutes or more a day as well as other exercise & has been extremely limiting calories since the start of covid. She has lost her period now for over 5 months and seems to have little to no estrogen. She always seemed to have low estrogen but not this low. Can she have PCOS and HA? If so, how does she get out of HA without making PCOS worse?

  6. Good Morning Doc, m on a 650 to 700 caloric diet but once a week I increase my calorie count to 1000 to balance and satisfy my cravings, But is there a possibility of having irregular menstrual cycle.

    A request for a quick reply, bit worried.


  7. Hi Dr. Lara, I have your book and I love it – teaches me so much!! My menstruation started to be less and less in quantity 6 years ago and I never knew exactly why…they told me first maybe PCOS, then no, now I am trying to diagnose myself and I reached the HA diagnosis – because 16 months ago my cycle stopped completely after entering keto diet (but it was very very little blood even before keto).

    My hormone results are: FSH 8.7, LH 7.8, Estradiol 32, Prolactin 8.3, Progesterone <0.5, TSH 1.41, T4 1.0, DHEA 143.

    Are these results signs of HA? What are tests should I do?

    The sonogram showed everything "perfect" as the doctor said….

    I would really really appreciate your help!!!


  8. Hi Lara.

    Thank you for such an interesting post. I was on a low-carb diet for 4-6 weeks and did intermittent fasting a couple of days a week. I felt great, but lost some weight and my period for 3 months. Got it right back a few weeks after eating more of everything, mainly increasing carbs. I did the low-carb test to see if it would help with endometriosis pain and increase chances of getting pregnant. The pain has eased, but obviously it didn’t help the pregnancy part!

    My fasting insulin level is 2.75 mU/mL. Does this mean my ovarian set point is higher and I need more carbs to ovulate? How do I know the optimum amount of carbs to consume? There’s so much information on how low-carb diets can help pregnancy and IVF cycles so it gets confusing finding the optimum level.

    Thank you,

  9. Hey Dr Lara, can sleeping late ( 4 am ) but managing to get 7 to 8 hrs of sleep by waking up late be a potential cause for HA? Does it affect hypothalamic functioning ?
    Thanks in advance!

  10. Hi Lara,

    I have IBD, coeliac disease and severe IBS. i suffer regularly with diarrhea and have worked with numerous dieticians and alternative functional medicine practitioners. The fastest and most effective way for me to deal with these flare ups is to fast for 16hrs e.g no breakfast or no dinner or to do liquid fasting. Whilst this is effective this is not ideal in terms of nutrition. i have had hypothalamic amenorrhea since my diagnosis of coeliac and it is a constant battle to keep my weight in the healthy range. I have recently been diagnosed with PCOS and a dexa scan indicated osteopenia. I am trying for a baby and have been prescribed metformin, progesterone which after bleed (i had bleed previously) will be followed with letrozole. I was wondering if you think these will be beneficial for me given the fact that getting sufficient nutrition can be a real challenge? Do you have any other recommendations/advice? Many thanks for all the amazing work your doing.

  11. I was on a low fat diet for about 10 months and lost a stone in weight, I now weigh 10 st 11lbs and I’m 5ft 8. I’m 46. My periods became very light, I changed my diet to eating more healthy fats, this month my period was much heavier, it took me by surprise, could this be a good thing? I felt like it could have been stored up blood, I have a retroverted uterus, what are your thoughts please? TIA

    • When you started eating more healthy fats, did that mean that you started eating more dairy? Because cow’s dairy can make periods heavier.

  12. My LH/FSH ratio (day 4) is 1.3
    So neither too low nor too heigh. Also, my BMI is 20 and I’m generally slim but with a bit of belly fat, which could be a sign of insulin resistance if I understood this correctly.
    But I’ve had irregular cycles since I started menstruating, so for about 10 years. Which makes me wonder if I really had Hypothalamic Amenorrhea, wouldn’t it have shut down my cycles completely? I’ve got no clue.

    • what does your doctor say?

      there are several other possibilities including gluten (non-celiac gluten sensitivity) like my patient Meagan in Chapter 1 of Period Repair Manual.

  13. Hi Lara,
    I was wondering if hypothalamic amanorrhea is more likely to be showing as really long absence of periods. Or can 40-60 day cycles be a symptom of HA as well?

  14. Hi Lara,

    If a woman has gained back a significant amount of weight since losing a period and has been able to maintain that weight for a few years, would it still be permissible to engage in physical activity while trying to regain a period? Given that the proper caloric adjustments are made, I am wondering if exercise might hinder the process of regaining a menstrual cycle?


  15. Hello,

    I am writing because I am really very frustrated right now. I have been waiting for my periods from last three weeks now.. There are cramps and ever day feels like they will appear.. I am a vegetarian and have now included eggs in my diet, but apart from that I don’t think I have enough protein in my diet. I don’t have PCOS and my body weight is just fine for my height. But, I really don’t understand what needs to be changed.. Is it the food? I have been trying all the home remedies for preponing a period but nothing seems to be working out for me..



  16. Hi Lara, we got pregnant with our first child easily. But it took almost 2 years to conceive our second child- (orthorexia, mini pill, HA, weight too low). But once I corrected those things, I regained my period and had a healthy baby. I did however have gestational diabetes and managed it with diet. My second son is 18 months old, and I stopped breast feeding him 4 months ago (when he was 14 months) I still haven’t had a period. My doctor says it can take a while after breastfeeding- all levels are within normal range, ovarian function looks good. Do you have any other ideas- have you seen this before? We would love a 3rd!

  17. How many carbs do you recommend for an active woman who weight lifts 4x a week for about an hour (mix of powerlifting and hypertrophy)? I stopped if and low carb about 1.5 months ago and shooting for about 200g carbs now. Still waiting for period. Also does having egg white cm multiple times during month signal period coming? Previously didn’t have any of this and no discharges at all.

  18. Hi,
    I’m vegetarian right now. Have been vegan mostly for 15 years. It seems to be repairing a lot of my health, but I’m almost into my third month of no period.
    It started the first month, a little brownish, dry? But didn’t finish, and I’m concerned about the blood in there. I don’t want it to rot or something.

    • If you’re not having periods (not ovulating), then something is not right with your health. It could be nutrient deficiency, but best to start by checking with your doctor.

  19. Hello Dr. Briden,

    I am writing to you for any advice you can give with regards to my niece, she turned 30 last year, she has been on the contraceptive pill since she was 17/18 years old! Her choice! But she is currently suffering terribly with acne on her face, to such an extend that she becomes quite upset at times about it, could this have anything at all to do with the contraceptive pill? Any help/advice/information that you can give me so that I can pass it onto her, would be greatly appreciated. She has appointment arranged to see a dermatologist, but she doesnt really want to go down the steroid route!

    Many thanks.

    Marie Spencer.

    • That’s interesting because girls usually go on the pill for hormone balance 🙁 I would encourage healthy diet, and Google hormone balancing foods. Peanut butter, although harder on the thyroid has helped me a lot.
      Also the pill can destroy a baby in the womb, many articles on that too.

    • Marie, is she taking a progestin such as levonorgestrel that has a “high androgen index”? Those drugs notoriously cause acne.

  20. Hello Lara – I recently had blood work done and my hormones tested here in Australia. My FSH was 9; LH 3 and E2 78 pmoL. I haven’t menstruated for many years after a history of disordered eating. I’m struggling to make sense of these hormone results and my GP didn’t really have any insight into them either. Any ideas on what they might mean would be appreciated.

  21. Hi Lara, thank you for your website! I went off birth control pills 2 years ago and since that I had irregular periods, but before I started using pills my periods were always regular. It took me 2 years (with hormonal pills, supplements and finally hormonal yoga) to get my regualr periods again. The problem is that I´ve started very low carb diet (keto) in january and my period has stopped again. Do you think that it´s possible that the cause of it could be the diet after 14-30 days? I went to the docetor, so he prescribed me duphaston for 3 months period. Thanks a lot for your reply.

  22. What does a fasting insulin result of 3.0 uIU/mL suggest? I notice this is out of your healthy range of 4-9 mIU/L. An impaired pancreas?

  23. You’ve essentially described me, here, Lara! I’ve been reading your stuff/book for about a year now, so much of this is nothing new, but that this post so perfectly explains the rationale behind my activities…it’s crazy. I have all 5 of the symptoms of not eating enough carbs, but with insulin-resistant type PCOS, I’ve been running scared from any and all carbs besides those found in nuts, coconut, avocados, and non-starchy vegetables for almost 2 years now. The fact that my period vanished for the first time ever just 1 month after beginning my ketogenic diet should have been a sign, but I was stubborn…wanting to see my blood sugar come down to a normal range and all. It’s 2 years later almost, and still no period at all. I wonder if you have any suggestions for reintroducing carbs…time-wise, portion-wise, etc. Should I maybe try to start with squash and a bit of sweet potato? Or would 1-2 days/week of a “carb-up” meal do the trick? I really love the feeling of being in ketosis, after all. And I realize that everyone is different, but I suppose I’m asking for anecdotal evidence from your clinical practice. Thanks so much!

    • Were you confirmed as having insulin resistance? What is your fasting insulin now? (you can send that as a private message if you like)

  24. dear Lara,
    you talk about fasting insulin level in your article , but what about levels of insulin after an OGTT in a lab:
    what would be the normal range after 30 mn, 1 hr and 2 hrs. No article talk about that , I have pcos and ask for this test lab and there was no normal range written with my results. Does 165 mlU/l of insulin is ok after 2 hrs ( my GP don’t know either)
    An article about this topic, would be great,medical articles only talk about the normal value for fasting glucose and results for glucose blood level after an OGTT.
    thank you,

  25. Hi Dr. Briden- I recently discovered your blog and LOVE the information. Thank you for the informed, readable, and relevant posts. As someone who’s had to do a lot of fine-tuning to stabilize my hormones, I can relate to a lot of it!
    I have a question regarding women and low carb. I am very aware that a low carb diet does not agree with our reproductive health, but have also noted the effectiveness of a temporary lower carb/anabolic diet direction for those looking to lose weight. And many studies suggest they are more successful long term, even when a more neutral diet is later returned to.
    So… as a nutrition student looking forward to eventual consulting, I’d love to know your opinion on this. For an overweight female patient, do you think a temporary low carb diet has a place in their protocol?
    Thanks a million!

    • Yes, women with insulin resistance can benefit from low carb and intermittent fasting. I usually first confirm insulin resistance with a blood test.
      And just as a further comment, post-menopausal women with insulin resistance can do very well on low carb.

  26. Dear Doctor Lara Briden,

    Greetings! I have recurrent bacterial and yeast vaginal infections. I currently have a really bad bacterial infection. I was given Flagyl, but I don’t want to take the drugs. I haven’t been able to come off the Fluconazole and Flagyl for years. Probiotics make my symptoms much, much worse. Can I use Oregano Oil? Berberine? Please help?

    Ciao, Justine

  27. Hi Laura, I’m so glad to have found your blog. I suffer from severe period cramps, black out, throwing up, you name it. I switched to the gluten free & dairy free diet a couple of weeks ago after my period, hoping my symptoms would improve after a few months. I started cooking myself and eating clean instead of buying microwave food (busy work alas), but I’ve been feeling extremely fatigue since I started the new diet. Then I had lower ab/ back pain and irregular bleeding / nausea, been to the doctor and did all the swaps/smears and all came back negative, and not pregnant. I’m so confused, could this be a side effect of the diet? Oh and I drunk soya milk and ate tofu at the beginning but then realised they affects hormone so I stopped. I look forward to your advice, many thanks. Lin

        • Is the fatigue still happening? It could be withdrawal from the inflammatory foods, but in that case, it shouldn’t last more than a week or so.

          • Hi Lara, thanks for the follow up, the fatigue has gone away, and the nausea stopped this week, but the pain is still there and discharge still doesn’t look quite right, had a phone call with doctor again and she still insists there’s no infection… could food affect texture and colour of discharge and cause bleeding??

  28. Confusded. If Androgens are normal from blood test. you have a very good diet with good starch…and ovarian looks good. Is it a good idea to try vitex to kickstart ovaulation. ? or maybe peony licorie.?

    • With my own patients, I base my clinical decision on LH. If baseline LH is high compared to FSH, then I don’t use Vitex. I also look for all possible underlying reasons that ovulation is not occurring.

      • Thanks a lot. I guess LH was not tested at the time my daughter had her blood test for possible PCOS…so better check that out before considering Vitex. Is R-lipoic acid to prefer before Alpha liopic acid to sensitive your insulin receptors.??

  29. Does anyone know if it is safe to take Fish Oil 1,000 mg EPA (around 2,000 mg Fish Oil), Evening Primrose Oil (1,000 mg) with L-Theanine, Rhodiola, Schisandra, Eleuthero? Is blood thinning a concern or should this be safe? Are there any resources where the information can be provided? No, my conventional doctor is not one and hiring a different one isn’t currently an option. I repeat: conventional doctors cannot and do not help when it comes to combining herbs and supplements. Neither are pharmacists. Where so we turn for help?

  30. I have hypothyroidism (hashimotos). I had a baby 5 months ago and am not breastfeeding and my periods at first were 2x a month (I was on spironolactone) then once a month last month and I haven’t gotten one at all this month (I stopped spironolactone as well). My periods before her were every 32 days. What is going on? I am not on medication form my hypothyroidism because it raises my testosterone and makes my symptoms worse (acne). Are there natural ways to help my thyroid and not raise my testosterone and get my period back on schedule? Thanks!

  31. Dear Lara,

    Please, do you have any suggestions what to do after having a heart scan with radioactive iodine injections in someone with hashimotos? My thyroid is very large and I think it might be related. Thank you very much

  32. Hi, Lara. I have had a sinus infection for about 10 months that never went away after several antibiotics. I saw an ENT who saw pus and infection in my sinuses and says I need surgery. I am very scared and reluctant and I was wondering if there’s anything natural I can try first? Thanks

  33. Lara, on your Twitter you posted a video with the caption “The real problem with refined carbohydrates (hint: it’s not insulin).” The video is not found when following the link, can you explain the answer? Thank you!

  34. Very intersteing post… Maybe you can eat “too healthy” .. thinking about intermittent fasting ..Could that be the reason for not getting a regular cycle…? Daughter has been 45 days late again…trying to be a detective now not an easy thing

      • . Thanks so much for reply. A good fasting insulin a bloodtest determines whether you are insulin resistance or not ? Even if the sympthoms points in another direction ? Should I trust the test result or the sympthoms….

  35. Hi Laura,
    i have lean PCOS, no insulin resistance and have to gain weight and have had no periods for month after get off the pill. Now i’m on the pcos diet low GL, no dairy, no gluten and protein with every meal and i take Ovasitol, Omega 3 and Vit. D. How do i know, that i get enough carbohydrates? At the moment my level is around 100 grams a day.
    Thank you.

    • Generally, if you don’t have insulin resistance, you shouldn’t restrict carbohydrates, or follow the classic PCOS diet. In fact, to do so, may have the opposite effect and prevent you from getting a period.
      You say you need to gain weight, so you need to eat a lot more carbohydrates than 100 grams.

      • Thank you Lara!
        The thing is…with starting the PCOS diet i had a period three times now…(too long cycles and a colour that tells me that my progesterone is still too low but my body reacts on the changes) I’m wondering: How can i find my way of eating for my type of PCOS? There are loads of recommendations and my mind is messed up because i don’t know, what’s right, whats wrong. I have to avoid an insulin spike but when i eat more carbohydrates so i have to balance they out with more protein? Can you give me some advice which lecture i could read to find my way with lean PCOS and no insulin resistance? Articles in pubmed or medline tell me that a low GL is important. But too much of protein may harm the kidneys and blood vessels…

  36. Hi Lara,

    thank you for another interesting post!

    I wonder if you have any thoughts on the effectiveness of myo inositol supplements in stimulating ovulation/managing PCOS. My new gynaecologist (in Germany) handed me a box of sachets yesterday and suggested I try it out. I was initially diagnosed with PCOS on the basis of high androgens and hirsutism, but had no insulin tests or ultrasound. Since then I have been trying to figure out what type of PCOS I actually have, because I am at a healthy weight, get regular periods, and the ultrasound yesterday showed no “string of pearls” on my ovaries.

  37. Hi Lara, thank you for another helpful post! I’ve been eating plenty of carbs and calories for well over a year, but I’m still with FHA. Any ideas? Also, could a slow thyroid prevent periods? Thank you!

    • Is it definitely FHA? As in, you’ve been screened for prolactin, androgens, zinc deficiency etc.? How low is your thyroid, because yes, that can be a factor.

  38. Hi Lara,
    I just wanted to comment that this article is 100% accurate! I’ve been on a long journey with hypothalamic amenorrhea (HA) and it all started when I severely cut my carb intake and went on a paleo diet thinking I was doing my body good. I lost my period for well over 6 months and had no idea why. I was so upset because I was trying to conceive at the time. I remember reading one of your other articles and started eating carbs and a normal diet and put on about 6 lbs in a healthy way. Sure enough my period came back in about 3 months and I was able to ovulate again!! I’m expecting my first baby now! I’m so happy I was able to overcome HA and be healthy again.

  39. Hello Lara, I think you actually read my mind!! Would a delayed period (35-40 days) be a result of possibly not eating enough? Love your work 🙂


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