We review the evidence on whether or not keto while breastfeeding is safe for you and your baby and how it impacts your breastmilk.
If you’ve been keeping up with the news at Abbey’s Kitchen, you’ve probably noticed that I talk quite a bit about the keto diet. This all started a few years ago, when my girl and fellow registered dietitian Abby Langer and I caused a bit of a stir with our video of us trying different keto recipes. Some people were, less than pleased, to put it very, very nicely!
To clear up some of my messages and to provide a 360 snapshot on how the diet actually works, I did a comprehensive review of the evidence of keto diet and its impact on weight loss, amongst other diseases like neurological diseases, cardiovascular disease and Type 2 diabetes.
Emerging research in diets always catch my attention, and as a dietitian, it’s my duty to stay informed and to put on my critical lens. So when I heard people taking on the keto diet while breastfeeding, I was instantly interested in learning about this new trend and its safety and associated risks. Plus, being a new mom, I always strive to learn the best and newest evidence to help support other moms and moms-to-be in this incredible journey!
So let’s get to it.
Keto While Breastfeeding: Is it Safe?
As with most super early-stage research, mice trials are what we start with and then work off of. Here in Toronto, researchers at The Hospital for Sick Children conducted 3 of them, each focusing on different phases of mices’ pregnancies and post-natal lives:
Before we discuss if its safe to breastfeeding while on a keto diet, let’s rewind and start with the effect of a keto diet during pregnancy.
Study #1: How Does the Keto Diet Affect the Embryo’s Organ Development?
Researchers studied mice separated into either a standard diet or a keto diet. After mating, the embryos were then tracked at 13.5 and 17.5 days gestation. What did they find? There were notable size differences – the keto embryos were larger at 13.5 days, and then interestingly, their growth slowed and became smaller than the standard diet embryos by the time they reached 17.5 days! In the keto embryos, the development of their internal organs were also altered. Could this mean potential organ dysfunction and behaviour changes later in life due to keto while breastfeeding? Still unclear.
This is some great starting information about keto while breastfeeding, however, it’s still not enough for us to draw conclusions yet, especially since this is a study of mice. But what we do know is that a keto diet during pregnancy may be linked to a smaller embryo size and altered rates of organ development. What about post-birth?
Study #2: How Does the Keto Diet Affect Breastfeeding and the Baby’s Growth?
Now the second study of this series on keto while breastfeeding. Similar to study #1, the researchers compared a keto and breastfeeding group to a standard group of pregnant mice, but this time, they focused on the mice and their offspring post-birth.
The results were fascinating. The keto mice who were lactating experienced severe physiological strain, and even went into ketoacidosis, a very dangerous complication where the body produces too many ketones, leading to high amounts of acid in the blood. In fact, they ended up dying within a few days after giving birth! This is perhaps due to the increased energy needs during lactation. As moms require way more energy than normal to produce milk, they burn more fat and create more ketones, pushing them way past the state of ketosis (the normal goal for someone on a keto diet), and into the dangerous territory of ketoacidosis.
To make matters worse, the keto while breastfeeding babies experienced slowed growth, indicating that the breast milk from the keto mothers was insufficient in its nutrition, volume or both. In this case, it was a lose-lose situation, for both the mom and the babe. Finally, the keto mice also had lower fertility, and if they did become pregnant, their litter sizes were much smaller than average.
Study #3: Does a Keto Diet During Pregnancy Have Lasting Effects into Adulthood?
Let’s talk about the keto diet and adulthood. The final study looked at the long-term effects of the keto diet by studying the adult offspring. After undergoing various physical and psychological tests, the adult mice of keto prenatal diets were show to be more physically active with a tendency towards hyperactivity, and exhibit less behavioural signs of anxiety and depression. So, I guess you can say these studies ended on a promising note? Let’s tie all the information about keto while breastfeeding together and see.
So – Is Keto While Breastfeeding Safe?
Looking at these studies, we know that a keto and pregnancy, as well as keto while breastfeeding in mice may be linked to their offspring’s organ development, metabolism, and behaviour well into adulthood.
Here’s a quick recap about keto while breastfeeding:
- Embryo sizes are notably smaller in pregnant mice on the keto diet
- All lactating mice on keto diet died, and their children were considered small
- Mice on the keto diet had higher rates of infertility
- Adult offspring of prenatal keto diets were more physically active, showed less signs of anxiety and depression
What does this mean, exactly? Although the lactating keto mice who died sounds pretty terrifying and is definitely something to think about, at the end of the day these are still mice trials, and with this premature research, it’s too early to comment on its safety.
Bottom line: moms have been breastfeeding on regular diets for a very, very, long time, and it has worked out wonderfully for them. I personally wouldn’t mess with a good thing.
High Fat Diets and Breastfeeding
Here’s what they found. The actual milk volume and the amount of protein in the milk were unaffected. However, the amount of fat in mom’s milk was actually much higher, resulting in the baby consuming more energy. This is because fat is higher in energy. Also, the amount of energy that the new moms burned, during rest phase and while breastfeeding was much higher if they were on a high fat diet, indicating a higher potential for weight loss.
But before all the new moms start upping their fat intake, let’s consider a few factors. There were only seven new moms included in this study. SEVEN! That’s hardly enough to generalize their health outcomes to the public. Also, these seven women were only on a high fat diet for eight days, and then a regular diet for eight days to compare. Do you think that trying a new diet for only eight days can make a significant impact? I don’t.
The Dangerous Case of “Lactation Ketoacidosis”
Alright, so in the earlier mouse trial about keto while breastfeeding, we saw that lactating mothers on the keto diet went into ketoacidosis and subsequently died. For all those who don’t speak science, ketoacidosis occurs when your body breaks down too much fat to meet your energy needs, resulting in too many ketones in your body causing a buildup of acid in your blood. In extreme cases, it can be fatal, so it goes without saying this should be taken very seriously.
Though there are no controlled studies that have investigated this on a human level (it probably wouldn’t pass ethics approval), there are eleven case reports of real women with lactation ketoacidosis while breastfeeding on a low carb diet. Very rare, but true and definitely worth looking into. These case reports are super interesting because ketoacidosis is traditionally a condition that affects those with diabetes, not lactating mothers!
Let’s look at one of those eleven case reports on keto while breastfeeding.
A 27 year old woman exclusively breastfed her 8-week old baby while following a low carb diet. She experienced vomiting and diarrhea, and was unable to eat anything for a few days – landing her in the ER. Turns out she had severe ketoacidosis and was treated quickly with intravenous fluids and told to increase her carb intake. Thankfully this was a happy ending and she recovered quickly and fully! (Read a few more case studies here, here and here).
Researchers and health professionals believe that this happens because energy demands are much higher during lactation. That, in combination with a low carb intake can push the body into lactation ketoacidosis. Thankfully, it can be resolved quickly from increased carbohydrate intake and intravenous fluids. So if you’re feeling signs of lactation ketoacidosis such as nausea and vomiting and you’re on a low-carb diet, please head to the emergency department ASAP!
So What Should You Eat While Breastfeeding?
I think it’s safe to say that the studies we talked about today, although premature, push us to lean towards an unfavourable approach when it comes to keto while breastfeeding (I’ve also previously touched upon it here). I don’t think we have enough research to say it’s not safe to breastfeed on the keto diet. At the same time, I also don’t think it’s worth the very clear risk. There are so many other eating patterns that people follow and new ones emerging all the time – so on a broader scope, you may be wondering how maternal diet impacts breastfeeding in general.
A few years, ago, a review of the best and up-to-date evidence explored this very relationship: maternal diet and the nutritional composition of breast milk. We were hoping this would give mothers more insight into how their diet can affect their baby. However, the evidence found by researchers was pretty diverse and, for lack of a better phrase, all over the place. The largest association they found was between fish consumption and omega-3 fats in the breast milk, and Vitamin C consumption and concentrations in the breast milk. But even then, the findings weren’t too significant.
Since the review found such inconsistent evidence about keto while breastfeeding, the researchers actually stated that this “work made [them] realize how scattered and weak the evidence is that is currently used in everyday clinical practice.” There’s a huge emphasis for more structured research into maternal diet and breastmilk composition and implications, with more clear standards for the definitions and study methods.
Contribution By:
RD2B Trista Chan
MORE BLOG POSTS YOU MIGHT LIKE:
If you liked this blog post discussing keto while breastfeeding, then you might also enjoy more blog posts on breastfeeding:
- Mom Guilt | My Breastfeeding Failure Story
- How Much Caffeine Can You Have While Breastfeeding?
- Cow’s Milk Protein Allergy in Infants | Should Breastfeeding Moms Go Dairy Free?
- The Truth About Drinking Alcohol While Breastfeeding: Will it Harm My Baby?
- Not Losing Weight Breastfeeding? Does Breastfeeding Cause Weight Loss or Weight Gain?
- The Ultimate Exclusively Pumping & Breastfeeding Essentials Guide
Abbey Sharp is a Registered Dietitian (RD), regulated by the Ontario College of Dietitians. She is a mom, YouTuber, Blogger, award winning cookbook author, media coach specializing in food and nutrition influencers, and a frequent contributor to national publications like Healthline and on national broadcast TV shows.
Rose McDonald says
I try to breastfeed to 24 months and beyond. This is my third child. I am currently breastfeeding a 15 month old and I have been trying to find data on whether or not the keto diet could be safely eaten at this point in my breastfeeding journey since my milk supply regulated long ago and my baby gets a solid percentage of his daily caloric needs from solid foods now. Breastfeeding a toddler is entirely different than breastfeeding a newborn in terms of milk production and milk composition and I’m not sure where to find information on the safety of this particular diet in this particular situation.
Abbey Sharp says
Hi Rose. Thank you for bringing this to our attention. We will look into it for a future blog post!
Jennifer says
Did you happen to look into what they were actually feeding the mice to get them into ketosis? I’m pretty sure they were only getting the equivalent of crisco shortening. Keto aside, I’d imagine a diet of vegetable shortening would have all sorts of negative health implications. I’d love to see some quality studies though as I’m currently breastfeeding and following a cyclical keto diet (i.e. I eat carbs whenever I feel depleted or if my supply drops). We all want to do what’s best for our babies and ourselves and its really hard to know what’s right. Hopefully there will be more studies in the future.
Georgina Hollenbach says
I was literally going to ask the same question. I have read a book where they mention that the studies done on ketosis have been done using margarine and vegetable oils which don’t even come close to the complex nutritional value of animal fats and protein that a traditional keto diet has. As much as I understand the concern, I think this study holds little to no value for an actual pregnant or lactating mother and her baby.
Drea says
Exactly what I found as well. Dr. Berg talks about what they actually fed the mice in one of his videos. You can find it on YouTube. It’s dangerous to create this article with out all the facts once again ruining the credibility of the diet. I breastfed my 11-month-old while on keto. He is now 2 and 8 months, at appropriate weight and highly intelligent & fully potty trained at 19 months. I’m now breastfeeding my 4-month-old while in keto. Every time I debated going on while breastfeeding, I would assess what I was eating and what I would be eating in keto. Much more nutrient dense foods. My baby is also benefiting from the sugar reduction as the was getting thrush and it went away after I started. I weighed her at the start and keep checking her weight daily. She is sustaining her weight thus far. She will also start solids as she is interested and has amazing head control already. This should help support the missing sugars she needs. Like lashing up bananas with some breast milk.
Samia says
Based on the literature, Ketosis is a state of survival where the body is in fight or flight mode. That is the opposite of rest and digest mode. I would imagine that it would be very difficult for the body to focus on making breastmilk while it is in survival mode. When I tried keto before becoming pregnant, I experienced all the symptoms of the so called keto flu as my body went into fight or flight mode : insomnia, constipation indigestion anxiety. Logically, I would say that keto is a bad idea while pregnant or breastfeeding and only ok short term when not pregnant or breast feeding…
Abbey Sharp says
thanks for sharing! i agree!
Darina P Lapkova says
I believe I finally got pregnant because I was on the keto diet. My hormones regulated, my energy was up, no brain fog, mood was boosted and then I got pregnant after so many years of trying. I was on keto during my whole pregnancy (clean keto). I had an easy healthy pregnancy, and my baby came out absolutely healthy. I continued the keto diet immediately after I gave birth, and my baby gained back his birth weight within 2 days. My milk supply is through the rough and I can see all the delicious fat in my milk. My baby is growing fast and healthy. Clean Ketogenic diet has been amazing for myself and my baby, not to mention I am able to treat my tumor with this diet as well.
Abbey Sharp says
Thanks for sharing!
Katie says
The diet given to these mice to induce a ketogenic state is VERY different than the “modified Atkins diet” that is being used to induce ketosis in the mainstream diets. I encourage everyone to research the work of Dr. D’Agostino if you want to nerd out.
I did not follow my keto diet during pregnancy because I was hungry for carbs but I have followed keto during breastfeeding. Both of my children hit their developmental milestones early and are in the upper 50th and 85th percentile for height and weight. Other studies HAVE been done and concluded that there are benefits to milk while on a keto/modified Atkins diet while breastfeeding.
With the exception of my pregnancies I have been keto for 7 years and I’ve never felt better!
Courtney says
Thank you so much for this informative post. I am currently breastfeeding my 5 month old who just started purées. I also breastfed my 2 older children until they were 1yo. I generally loosely follow a paleo diet and have since my first was born. With my third i tried keto and noticed an IMMEDIATE and significant decrease in my milk supply and I’m an over producer. Also when my daughter was 6 weeks old i experienced the exact symptoms described above for severe ketoacidosis and almost went to the ER but found a walk in with no line to try first… the doctor determined it was the flu and told me to follow the BRAT diet and drink Gatorade. On Monday I went to my OB and he had me tested for all kinds of viral infections including the flu and I had nothing and he couldn’t figure out what was going on in my body. I finally talked to a doula who told me I needed to eat to repair my root chakra with meats and root vegetables (high carb / starchy vegetables) once i followed her advice my body went back to normal. I have that lingering 10 pounds left so i was researching if my decrease in milk supply was coincidental and was thinking of trying keto again but after this article i will not be until after she’s weaned if necessary and I’m so appreciative of your research and finally finding a reasonable explanation for what i experienced!!
Abbey Sharp says
So sorry for your experience and so glad this article helped! Thanks for sharing
Yaz says
Hi Abbey! Thanks for the information. My question is I have breast fed until my first 2 children were 2.5 years. My 3rd child is now almost 8 months and starting to eat foods as well as breastfeed. Once he starts eating more food and not relying on exclusive breast feeding, do you think the risk of lactation ketoacidosis is still as concerning?
Maria says
I went on a keto diet /low carb diet while breastfeeding because my baby was epileptic and I thought having more fats and less processed sugar and carbs in my diet would be beneficial for his brain. As a fringe benefit, I lost the baby weight. My son who had trouble gaining weight is now an average baby and is developing fine. It’s hard to say whether his seizure disorder has improved or not. He gets seizures every 2 weeks and we’ve never medicated except for cbd oil. I eat a moderate amount of carbs and make sure I don’t go into ketoacidosis. I also drink a tonne of water and top up with salts/electrolytes.
Abbey Sharp says
Glad your baby is doing okay. Thanks so much for sharing your experience with us Maria
Robert Reny says
Thank you for sharing such an informative article I will be sharing this information with my sister, she is 9 months pregnant and is very concerned about her weight and wants to do dieting after the baby is born.
Abbey Sharp says
Great, hope it’s useful
breanna says
I followed a 20% carbs, 60% fat, 20% pro diet while pregnant. I religiously kept a food log, tracking macros, vitamins and minerals. I did this with the full support of my OB who is also a fetal health specialist. I was attempting a VBAC, and my first child was on the large side, so we were trying to keep the baby at a reasonable and safe weight for a natural delivery. Long story short, I only gained 23 lbs, and had a completely natural vaginal delivery giving birth to a nine and a half pound baby boy. Despite my dietary efforts, he was still a quarter pound heavier than my first child (I did not have GD with either pregnancy), but he’s very healthy, slaying his developmental milestones, and quite possibly the happiest baby I’ve ever met. I think it was definitely worth it. I didn’t gain a lot of weight and was able to lose it easily. And most importantly, my baby is VERY healthy.
Abbey Sharp says
Great to hear. Thanks for sharing
Jenn says
I tried keto with baby #3 when I was 6 mo postpartum. At his 9mo dr apt later he hadn’t gained weight and I was told to avoid keto while breastfeeding. My supply hadn’t dropped, but he wasn’t gaining weight and my milk seemed more liquid and less fat. I felt terrible and wasn’t worth the 10lb I lost. I’ll try again once I’m done nursing my baby girl who is now almost 9-mo old.
Abbey Sharp says
Thanks for sharing 🙂
Anita says
This is so interesting, thank you!
I’ve been LCHF (keto, though I don’t religiously count carbs, so if a little too much pumpkin takes me over, so be it) for about 4 years, mostly to help manage CFS/ME and POTS, after a specialist informed me I did not process carbs correctly. Weight loss and maintenance was a happy side effect.
Recently I was pregnant, and my doctor advised I incorporate healthy carbs back into my diet, which I did. The weight gain was unfortunately immediate – I was 6 weeks pregnant, eating a balanced diet and gained 6kg. Unfortunately I lost the baby, but as we’re trying again, it’s definitely nice to have some scientific basis to help us make these decisions!
Thank you for being thorough and even handed with your advise as always.
Abbey Sharp says
Totally. Thanks for sharing Anita
Kate says
As a dietitian and mum I would be interested in doing some research on a high fat (regular carb and protein diet) one day. I have two sets of twins and exclusively breast fed both for 6 months and continued until 14 months. I was a ravenous animal while nursing I had to eat a crap ton of food to keep up my milk supply. However anecdotally I found consuming a lot of fat really boosted my supply. I actually added extra fat to my diet to keep up my supply. While I certainly didn’t limit other macronutrients (so overall caloric intake was indeed high) the fat was my secret weapon for sure!!
Abbey Sharp says
Very interesting. Fat can do wonders for us, however I think there’s not enough research to suggest going low carb at the same time is best though. Thanks for your thoughts Kate!
Jessica Levinson says
Great post! Thanks for the research and information!
Abbey Sharp says
Thanks Jessica
Tanya says
Thank you for sharing this information. It was very helpful. I used to be on a Keto diet prior to becoming pregnant. I was recommended by my doctor to stop once I became pregnant. My son is now 9 months old and I’m still breastfeeding which I intend to continue. I was afraid of my supply being affected so I have stayed away from Keto. The issue though, is that I’m not losing the baby weight.
I was thinking of going back on Keto but after reading this I think I’m going to hold off until I decide to stop breastfeeding.
Any advice on how to lose weight while breastfeeding? I’m active and workout 4 times a week but I’m not losing that stubborn 10 lbs.
Thanks!
Abbey Sharp says
Awesome. Thanks so much for your comment Tanya
Imma says
Wow! I am diabetic and doing exclusive breastfeeding. I am considering the keto lifestyle though baby is 4months old. Am really confused
Kelly says
I always love that you do your research. A very helpful, informative article!
Abbey Sharp says
So glad! Thanks Kelly
Emily @Sinful Nutrition says
Such an interesting topic. I never even thought about this before!
Abbey Sharp says
Very cool
amy says
wow i am planning to keto diet when my baby 6 1/2 month now,and here the topic let me stop this thought.Its very helpful for me,thank you for your research.This is very convincy&full information
Abbey Sharp says
Thank you Amy
rebecca says
thanks for sharing! I never would have thought of ketoacidosis in breastfeeding-so interesting!
Abbey Sharp says
Yeah, very. The research is fascinating
Deborah Brooks says
I don’t know too much about the keto diet as it’s not too vegetarian friendly. So much more to think about these days with pregnancies
Abbey Sharp says
Yes, totally. Research keeps coming out