Breastfeeding on a low-carb diet – is it dangerous?

Is it dangerous to breastfeed while on a low-carb, high-fat diet?

Recently, the journal of the Swedish Medical Association published a case report (summary in English) of a woman who, six weeks after giving birth, had to be hospitalized for severe ketoacidosis. Luckily, she recovered quickly and her numbers were back to normal the next day.

Ketoacidosis is a dangerous condition, most often seen in type 1 diabetics with acute insulin deficiency. In rare cases, ketoacidosis may occur in non-diabetics after prolonged periods of starvation or inadequate food intake, in which case it typically occurs in combination with stress or other medical conditions.

The woman in this case had been eating low-carb, high fat for a long time before the incident. After giving birth however, she had suffered flu-like symptoms of fever, nausea and a complete loss of appetite. Despite this, she was still able to breastfeed her baby, which of course ramped up her nutritional requirements.

The case study report brings up the woman’s low-carbohydrate diet as one possible contributing factor to the situation. However, as soon as the media found out, they immediately exaggerated this possible contributing factor to the guaranteed sole cause of the condition (which, as we shall see, is unikely):

In the woman’s own words

The woman described in the case report in the journal contacted me of her own accord through common acquaintances. She tells a different story from the one perpetuated by the media:

What isn’t made clear is that I, the breastfeeding woman, had been eating LCHF for approximately six years before this incident, but, because of stress during my second pregnancy and after childbirth I suffered loss of appetite. This led to more stress as I wanted to eat, but my body said no. I ate whatever I could keep down: crackers, yoghurt, fruit… The problem was that I barely consumed any food at all, and didn’t get enough energy from fats or carbohydrates..

I came down with a fever that lasted a whole week, this was two weeks before I was admitted to Mora [hospital] and during that week I ate almost nothing, I mostly drank water. And while I wasn’t eating, my daughter was, which naturally depleted me of nutrients. To say that I ate a low-carb diet and got sick is just wrong, I regrettably ate nothing and whatever I ate was actually carbs.

I still do low-carb, but the difference between now and when I got sick is that now I actually eat. I’m healthy and haven’t had any issues for a year now. I completely breastfed my daughter for another 10 months and didn’t feel bad at all. (Well actually, I did feel psychologically lousy because of what the doctors threatened and accused me of, but nothing else) :)


After reading the woman’s own story, this seems to fall under the category of ketoacidosis induced by starvation and sickness. It’s well-known that starvation can, under extreme circumstances, result in ketoacidosis — and this may be just what the demand of breastfeeding contributed to.

Whether the low-carb diet contributed to the course of events or not is unclear, but it is possible that it could have been part of the combination of factors behind the development of ketoacidosis (even though the woman in question hadn’t been doing low-carb the last weeks prior to being hospitalised).

Many women and mothers have shared their stories of eating a low-carb diet with great success, and without any issues at all for breastfeeding. Theoretically however, it’s possible that a strict low-carb diet in rare cases is just too demanding during lactation.

During lactation, the body produces carbohydrates for breast milk. If you’re adhering to a strict low-carb diet without carbohydrate, it means your body will have to produce more carbohydrate than people who don’t have babies to feed. Especially in combination with a flu or or starvation, this may in extreme cases be too much for the body to cope with.

Note that new diabetes drugs that leak glucose from the body (SGLT2 inhibitors) can also in rare cases result in ketoacidosis. The loss of glucose on these drugs is some ways mimics the effect of breastfeeding.

According to the journal of the Swedish Medical Association, there have been 5 cases reported worldwide on ketoacidosis during lactation, of which 2 are possibly linked to low-carb and 3 are linked to starvation. Another new case report on ketoacidosis during lactation and low-carb eating was published just recently, raising the total published number of suspected cases to 4.

My recommendation

Although these cases appear extremely rare – a handful of published ones in modern history, of which all seem to have ended well, with the woman recovering rapidly – they are worth taking seriously.

In my opinion, it’s a good idea to be watchful if you choose to breastfeed on a low-carbohydrate diet. Perhaps the best alternative is to go for a slightly more liberal low-carb programme.

Bearing in mind that breastfeeding consumes carbohydrates, it may be unnecessary to aim for less than 50 g carbohydrate a day. This would, in theory, correspond to a strict LCHF diet for non-breastfeeding people. Although the risk of negative consequences of a very strict LCHF diet while breastfeeding is probably minimal, it’s an unnecessary risk to take.

So how do you recognize early symptoms of ketoacidosis while breastfeeding on low carb, in the highly unlikely event that it should happen? You’ll get abnormally thirsty, headache and nausea and generally feel weak and sick. In that case you should significantly increase the amount of carbs and fluid you ingest – and seek medical attention immediately if you should keep feeling worse instead of better.

The most important thing is, regardless, to get enough food and nutrition overall when breastfeeding. If you’re finding it hard to keep down anything of nutritional value (for example, because of some illness), you should contact medical professionals for advice.


“Young Mother Nearly Dies From a Low-Carb Diet”

More potential problems on low carb

Check out our full guide on common low-carb side effects and how to cure them. Alternatively you can jump right to the section that interests you:


  1. Vicki Higgins
    Re the case of "ketoacidosis" in lactation:
    It would be interesting to see some of the blood glucose results for this woman, as well as the ketone levels - I am a retired vet, so wonder if this s a little like the ketosis that occurs in some high producing dairy cattle early in their lactation when they cannot get sufficient intake to maintain the high milk output without losing condition and getting higher ketones, but in the face of lowered blood glucose - ie - not the ketoacidosis of type 1 diabetes - high ketones and high glucose - but as suggested above, the high ketones of essentially starvation. One standard treatment for these cattle is a bolus injection of glucose
    Replies: #2, #19
  2. greensleeves21
    The old Atkins community group heard Dr. Atkins once caution against this theoretically possible scenario & ever since their official recommendation was that breastfeeding moms should never fast, get 3 square meals a day & eat 60-70 carbs a day to avoid it. So I guess there is some validity to that old recommendation to avoid such rare cases.
  3. George Henderson
    I'd like to give some biochemistry background to this story -
    Liver cells and some specialised brain cells are the only cells that make glucose, and the liver is the only organ that makes ketone bodies in appreciable amounts.
    Ketone body production by the liver in starvation and nutritional ketosis is the byproduct of glucose production. The synthesis of glucose removes oxaloacetate from the TCA cycle, and without oxaloacetate the acetyl-CoA from fatty acid oxidation cannot enter the TCA cycle and is used instead to make ketones that are exported from the liver (they are used by the TCA cycle of other cells that are not making glucose, therefore are not deficient in oxaloacetate).
    Type 1 diabetics get diabetic ketoacidosis because without insulin high levels of glucagon stimulate excessive production of glucose by the liver. The dumping of glucose through the kidneys causes dehydration and a loss of alkaline electrolytes, causing the concentration of ketones and acidity.
    In the case of lactation on a low carb diet, not only does the mother require glucose to be made by the liver for her own needs, but extra glucose is also required to make lactose (glucose plus galactose) in the mammary gland. The lactose requirement of a 10 month old child must be getting fairly high, because human milk is not so low-carb, so the amount of ketones generated by the liver will be higher than usual. This could be problematic because some alkaline electrolytes are also being lost to the milk.
    In this case, because the mother was sick, she was likely losing electrolyes in body fluids, and of course she wasn't eating any in her food.

    As Vikki Higgins says, this is common in animals, especially under modern conditions of high milk production, or as a result of multiple births.

  4. George Henderson
    I've sought more insight into this problem by looking for non-LCHF ketoacidosis cases.

    There are cases of lactation ketoacidosis - all in non-diabetic mothers - while

    - being fasted NPO before an operation
    - eating a normal diet and feeding twins 5 years after gastric bypass surgery
    - eating a low calorie diet (not low carb)
    - after gastric bypass surgery
    - eating high protein low calorie diet

    and one where LCHF seems to have been eaten,

    - switching to ketogenic LCHF diet during lactation (10 month old)

    This last one I think is telling us something - lactation ketoacidosis is unlikely in a fat-adapted person, because ketone and non-hepatic FFA clearance has increased, electrolytes are back in balance, and stress hormones have normalised. But maybe trying to ketoadapt while lactating is like trying to ketoadapt while running a marathon.
    In the case of lactation, the doubled demand for glucose GNG could cause a sudden rise in ketones while ketoadapting - making it too easy to get into deep ketosis before the body has fully adapted to utilize ketones or regulate ketogenesis. But a person with T2D or PCOS has some protection because their insulin is higher, it's not going to drop out easily, and this will slow down lipolysis and ketogenesis. I couldn't find a case study of ketoacidosis of any kind in a person with diabetes on a low carb diet (I also couldn't find any non-diabetic ketoacidosis cases who were male).
    It seems to me that in a woman who fat adapts before conception, especially if she has a hyperinsulinaemic condition as her reason for LCHF eating, the conditions that predispose to ketoacidosis are reduced, especially if sudden weight loss is avoided.
    On the other hand lactation, by diverting sugars into milk, should also increase glucose tolerance.

  5. Amber O'Hearn
    There must be more than 5 case studies out there. This one from 2012 already claims to be the 5th:

    Notable in that study, BOHB is just over 9. While I agree that this is high, and don't dismiss the symptoms, I don't think that qualifies as "severe ketoacidosis" at all.

    The woman is sick from starvation, a *marker* of which is high BOHB. That doesn't make high BOHB a sickness.

    Replies: #6, #10, #29
  6. Bjarte Bakke Team Diet Doctor
    And yet, isn't it important to discuss and look out for such cases Amber? I'd rather us in the LCHF world be a little too paranoid than a little too complacent.
  7. George Henderson
    I agree Bjarte. If someone googles "risk of lactation ketoacidosis on a low carb diet" or "acute porphyria low carb diet" I want them to find that the most informative, scientific, and unbiased accounts are on low carb websites.
    Even marginally severe ketoacidosis is potentially risky in malnourished individuals because cationic electrolytes - sodium, potassium, calcium, and magnesium - tend to be sequestered by an excess of anions, and a relative deficiency of any of these can affect heart contraction and QT interval.
    The "all you can eat" aspect of LCHF is a protective feature that should be stressed during the induction period. Starvation ketosis should not be mistaken for a substitute for nutritional ketosis - with the emphasis on nutrition.
  8. Devayani
    Hi, I have a question for you. Since I feel you are a person who can guide me.. My kid is going to turn 2 in July and it's been 3 days that I m following a ketogenic diet. I still breastfeed him on demand.. Past two days were difficult as my body was trying to keto adapt but today I suddenly feel energetic instead.. I still am a bit apprehensive whether to follow this diet or not.. Whether my child has to bear the brunt of my blunder... Is it OK to feel like this initially... Pls do throw some light.
    Reply: #9
  9. Zepp
    Dont overdo anything if you still want to breast feed.

    Make it a a smoth transitation.. lets say three months?

    The first thing you notice is glucose shortige.

    The second thing is that other things tryes to compensate for that.. some of those things are sk stress hormones!

    Its temporarily.. 1-4 weeks.

    But how to make a smother transitation.. cut all sugars and flour.. rise your veggies and keep som tubers.

    Mayby, mayby.. you are healty and dont need to do a harsch ketogenic diet at all?

    Ketones is not the goal.. they are sub markers that says that one dont eat to much carbs.

  10. George Henderson (@puddleg)
    In pregnancy the threshold for acidosis is lower because of changes in blood gas concentrations, so you get a lower pH at any given ketone concentration. This effect may persist into lactation, but I'm not sure.
  11. Lissa
    You should naturally be hungrier while breast feeding. Instinct should tell you. Simple.
  12. Katie Stone
    This confuses me because I am currently pregnant with gestational diabetes now we have been told not to cut out carbs but to keep our blood sugars within a particular range. The carbs we have been told to eat are whole grains, seeded ect. Now as the pregnancy progresses you get more intolerant to carbs. I am now on insulin and any type of carb sends my blood sugar sky high. Most gestational diabetes goes after the birth, well its most likely there but you are classed as pre diabetic. As they lower the diagnostic threshold during pregnancy. They are already pushing breast feeding as the best option and don't get me wrong I breast fed my other three children but if you remain diabetic after the birth and breast feed this could make you really poorly. Especially if you cannot tolerate any kind of carbs at all.
  13. Gentiann
    Insulin???? that means you are still eating too much carbs...why don't you try to get your carbs strictly from non starchy vegetables and see how your blood sugar responds? however, be careful to monitor your blood sugar closely, you may not need as much insuline
    Reply: #31
  14. Linnea
    Please I've been looking everywhere for information about breastfeeding and
    LCHF but can't find what I'm looking for. I've
    been on a low carb diet for many years and high fat for a while now. I had my 2nd baby 10 weeks ago and as with my first, breastfeeding is going well. I eat LCHF when I'm hungry and try to listen to my body. The problem is the same I had with my first baby, I gain a lot of weight, about a kilo per week instead of loosing weight. Could it be that my body is calling for carbs, needed for the milk, but as I'm eating mostly fat, my body is not satisfied and sends hunger signals. Please help, I don't want to stop breastfeeding but I don't want to keep in gaining weight like this either...
    Reply: #16
  15. Ashley
    I was hospitalized in 2014 With metabolic acidosis while breastfeeding and doing adkins. I was unaware of the health implications and ended up in ICU after 9 days on the diet. I was treated with sodium of some kind and they did an arterial blood stick in my wrist to test my PH level. I almost died. My heart and kidneys almost shut down. I went to hospital after two days of what I thought was keto flu, I awoke in the morning to a horrible headache, and severe weakness. Could hardly walk. Dr. In ER said I was "tachy". My blood sugar was so low it was around 16 or something
  16. Talena

    I am still breastfeeding my 20 month old. I restarted my LCHF diet after delivering and lost all of my pregnancy weight and even more so (this was after my second baby and I hadn't lost what I gained from first one really). I was 190lbs at birth of first child, 220 at birth of second (dropped to 195 without going on diet), and after I got on the diet I was at 165 in 18 weeks after delivering second baby. I did the LCHF diet, I had to add more carbs for my milk production, but I looked at slow burning carbs vs the high burning carbs (look up low glycemic carbs). I would have half a sweet potato, or something like that and it helped. You have to know your body, if you feel odd, or your milk production is dropping some, slowly add more carbs, but you want to have good carbs not fast burning ones.

    Reply: #18
  17. Linda
    Thank you for posting this. I've been LCHF for a few years now. I had a baby Dec., 2015. Before I got pregnant, I was doing all kinds of LCHF experiments on myself like the egg fast and eating a steak a day. I was very active in yoga. After I got pregnant, I wasn't tolerating my diet; always throwing up my eggs and steak. Around 3 months pregnant, I started eating potatoes with my eggs. Let's say it was a horrible choice. By December, I was very much a sugar burner consuming ANYTHING AND EVERYTHING WHICH Resulted in a whopping 80lbs weight increase.
    I also breastfed my baby...and still am 16 months later. I was afraid to go back to my LCHF lifestyle. When my baby turned 1 year, I told myself I had met my nursing goal and if my mill dried up as a result of my diet, I still made it. If it doesn't dry up, everything else after 1 year is a bonus.
    Well...its been frustrating! Because I'm an experienced LCHF person, I took my electrolytes seriously. I went down to zero carb and cut my coffee out of my diet. I was around 245 pounds at my heaviest, and even though I am very strict and even measure my blood glucose and ketones, I am only 220lbs 4 months later.
    Now...I am still producing milk. We nurse about 3-4x a day. She is also a low carb baby!!!! I have blood glucose levels that go all over the place from 87 fasting to 116 fasting! Now the 116 fasting only happened once, but still I'm very surprised my glucose is that high for how strict I am.
    I also went back to my gym. I do yoga, spin, and a body combat class. I go 4x a week and do 2 classes a day. I exercise because I love it and used to be a group fitness instructor. It makes me happy. I don't wish to let go of it, but I will if it is the problem.
    Any thoughts on why I am not losing as fast as I'd Like? Any thoughts on whether or not this could be water retention? I admit, I don't drink as much as I should. I drink when I'm thirsty. Someone above said nursing mom's have higher glucose levels. Would this explain why I'm not losing?
    PS. My baby has had zero issues nursing with me in ketosis and only been sick once her whole life, and I believe it was brought on by teething.
  18. Kathryn

    I am still breastfeeding my 20 month old. I restarted my LCHF diet after delivering and lost all of my pregnancy weight and even more so (this was after my second baby and I hadn't lost what I gained from first one really). I was 190lbs at birth of first child, 220 at birth of second (dropped to 195 without going on diet), and after I got on the diet I was at 165 in 18 weeks after delivering second baby. I did the LCHF diet, I had to add more carbs for my milk production, but I looked at slow burning carbs vs the high burning carbs (look up low glycemic carbs). I would have half a sweet potato, or something like that and it helped. You have to know your body, if you feel odd, or your milk production is dropping some, slowly add more carbs, but you want to have good carbs not fast burning ones.

    Did you restrict your calories?

    I did LCHF for a while but didn't track anything; I didn't loose any weight.

    I'm currently doing the two week challenge on diet doctor but it puts me way above my calorie intake and I'm concerned it's going to stop
    My progress.

    I'm breastfeeding my 8 week old so I'm adding in the additional 20-40 carbs.

    Just hoping to get some more info from someone who's done it and it worked

  19. Lucy Ford
    The Australian Breastfeeding Association published the glucose and ketones of a number of these cases and referred to a bovine lactation study.
  20. Melissa
    I'm finding it impossible to lose weight. I am breastfeeding my 14 month old (she still takes in about 600 calories a day from milk, judging by her solid food intake), hypothyroid (switched to Cytomel recently due to borderline high RT3 & other issues on NDT), and should have had a 400 calorie deficit daily (on average, since 12 weeks postpartum, assuming BMR + 1-2 hours per day on an arc trainer & not including carrying around my baby all day in a Moby; I weigh/measure all my food). I lost down to 253 (prepregnancy weight 243, I am 5'11"), then went back up to 281 in the past year, despite eating like an organic, whole foods saint & working out daily. My thyroid hormones have definitely been too low, but it's never been this hard to lose weight before - and that's saying something, as my max avg loss has been 10 pounds a year (sad, I know) for 7 years prior to conception. My metabolism must be 1,000 less than prepregnancy, and I was almost 40 pounds smaller!!! /rant

    I am thinking of trying low carb again (been years since I needed it for management of Type II, exercise has been enough). I'm desperate. I would appreciate any advice/anecdotes/feedback.

  21. 1 comment removed
  22. Aby
    I am on the keto diet while breastfeeding my almost 3 year old. I've had no issues thus far. I've noticed no change in milk production. I've been on the diet for 2 months following it strictly with ketones in the 2.1 range with the blood readings. I've lost weight as well and my health has improved drastically. High blood pressure is now normal, cessation of migraines I used to experience monthly, and my menstrual cramps are gone as well as resuction in flow which was severe before.
  23. Ian
    I think the advice should be to take at least 10g of salt a day as well as drinking a lot of water. It is clear that dehydration increases the risk of ketoacidosis, we also know that if someone is not taking in any salt that water on its own will not prevent dehydration.

    I expect the anyone who is breastfeeding and not taking in food should be using one of the commercial powered (for example Dioralyte) that are sold to prevent dehydration, the breastfeeding should be enough to undo the harm of the glucose content of these powders. (A glocose free electrolyte drink if BG is comfirmed to be high could be a better option, but it is hard to get at short notice.)

    Also if someone who is breastfeeding is not able to eat for more than one or two days they should clearly be going to see their doctor.

  24. Brandy
    I am currently breastfeeding my 9 month old. I started LCHF approximately 4 weeks ago with a 50g carb limit. I am now down to 30g, but considering going back up to at least 40 for as long as I am breastfeeding. I just wanted to say thank you for posting this - I haven't found much information regarding the risks while breastfeeding.
  25. Lydia
    I am breastfeeding my 4 month old and decided to do a GAPS intro because my crohns was bugging me. Its pretty much meat, stock, simmered veggies, and avocado and some tea with a little honey for a few days. Its ketogenic. This morning I woke up so sick. I was nauseaus, trembling, weak (like I felt like I had to lay down), and my resting heart rate was 107. The was my 3rd day of eating like that. I ate a banana, and while I feel better, and I still feel drained and flu like. I am going to add more GAPS friendly carbs today so this doesnt happen again.
  26. Dawn
    I breastfed all 3 of my girls. 1 Had nutritional difficulties so she nursed for years. All 3 are healthy now. Low carb and low fat diets are not particularly safe for children. Remember that sugar makes us fat, right, and those kiddos need to grow. That's why breastmilk has so much glucose. That said your body should create enough glucose for baby as long as your protein and fat levels are high enough. On a ketogenic diet though you will need more protein and fat to feed the baby and you will stay in ketosis even with around 50 gm carbs if you are nursing frequently. If you can't eat you must supplement your body because your body can't create out of thin air. Even if that means drinking Gatorade or something and getting back into ketosis when you are well again. Also your electrolyte needs will be higher because you are supplying baby as well. I recommend having a medical provider checking labs fairly frequently until you are experienced at both keto and breastfeeding. Remember baby is only a baby for a short time. Cherish it.
  27. Melanie
    I'd suspect severe dehydration is a player in this equation as well. It is common to both breast feeding and to the flu like illness.
  28. Jessica
    I started eating a zero carb diet when my baby was 6 weeks old. I never noticed any issues, but felt better in a lot of ways. 18 month later and my baby is still breastfeeding. She's grown well and never needed formula. I had no idea I needed carbs to breastfeed. Maybe adaptation can be tougher while breastfeeding for some, but my personal opinion is carbs are not required for human health.
  29. Mariana avendaño
    Existe poca información acerca de esta dieta en periodo gestacional . Podría apoyarme con reciente información .
  30. Lacey Kreft
    It seems to me that context matters a lot. If baseline diet is low carb, then the body is more adapted to burning fat for fuel and converting protein into glucose via gluconeogenesis as needed. Diabetic ketoacidosis is a very specific metabolic derangement where both ketones and glucose are high. I suspect high cortisol in combination with calorie deficit could cause this to happen (or eating ONLY carbs when physiologically insulin resistant due to sustained low carb diet... Sounds like the worst possible choice to me). Just listened to Dr Paul Saladinos podcast regarding CGM and I have been adding in some honey with breakfast and lunch (otherwise carnivore with adequate fat and electrolytes). I have been breastfeeding my 3-week-old. Last night woke up hungry at 3 am (last meal at 6:30 pm). Tried to go back to sleep which went poorly. My mind was racing. Suspect hypoglycemia but unsure as my baby frequently feeds at 1.5-3 hr intervals so my letdown reflex may have woke me. Got up at 5:30 and checked glucose: 79 and ketones: 0.4 so I suspect I may have to eat more for dinner or add a fat/protein snack before bed. I'm hoping the CGM will help me tinker with increasing carbs at a level to avoid glucose spikes (trying to limit fiber as my gut objects during times of now) and adding more protein to avoid nocturnal hypoglycemia with resultant spikes in cortisol.

    Anyway, I am overall really glad I did mostly low carb/carnivore before, during, and after pregnancy. Second and third trimesters I went very low (mostly zero) carb. I found I needed more carbs my first trimester due to increased insulin sensitivity. This scared me a bit because I gained 10 pounds but I lost fat during 3rd trimester for a total weight gain of 33#. I weighed about 5# more than prepregnancy weight at 2 weeks postpartum and staying steady. Makes me pretty pleased with myself 😉 Anyway, it irritates me that the only s*** you can find online is that you need to make sure you're not doing low-carb. I have done pretty well keeping carbs as low as possible while still feeling good. Overall it's been my experience not to skimp on the protein, load up on electrolytes especially salt (I mix 5 grams into lemon water and down it 1-2x per day in addition to salting food to taste and taking magnesium glycinate), monitor sleep/stress, and titrate in carbs if needed. Cheers!

  31. Ingrid
    No, it does not mean she’s eating too many carbs. I’m a 100lb, 5’6” woman, and when I had gestational diabetes, could not consume so much as a tablespoon of cottage cheese or a baby carrot without my blood sugar skyrocketing. I ran on the treadmill after every morsel for an hour to have perfect blood sugar numbers, and an A1c of 5. But my caloric output was about 8x my input, and when my weight dipped to 110lbs at 8 months pregnant, I fell into a rare type of ketoacidosis without ever having had high blood sugar. I was hospitalized, tested, told that my pancreas simply stopped producing insulin (rare for gestational diabetes, but possible and more common in thin mothers who have GD, and far more serious than insulin resistance). I was put on insulin because my cells could not uptake any glucose without it. I would have died without it. So please don’t shame this pregnant woman when you are so painfully misinformed.

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