Guest Blog Post: Is It Safe to Go Low Carb During Pregnancy?
Is It Safe to Go Low Carb During Pregnancy?
With the wide adoption of low-carbohydrate diets, many people question if they are safe during pregnancy. While quite a few women use a lower carbohydrate diet to conceive (since they are especially useful for women struggling with infertility[1]), most medical professionals discourage women from continuing this diet during pregnancy. I find it ironic that if you tell your doctor that you plan to eat low carb during pregnancy, they’ll say it’s unsafe, but if you say you plan to eat a diet based on fresh vegetables, meat, fish, eggs, dairy, nuts, seeds, and a little fruit, they’ll encourage you to stay the course. The controversy over the safety of low carbohydrate diets in pregnancy stems primarily from misconceptions around ketosis. It’s incorrect, but widely accepted, that ketosis during pregnancy is harmful to a developing baby.
When I first dove into the research, I was shocked to find that studies on healthy, non-diabetic pregnant women (eating a “regular” diet) show a marked elevation in ketones after a 12-18 hour fast, which is akin to eating dinner at 8pm and having breakfast at 8am (or skipping breakfast entirely).[2] What’s more interesting is that pregnancy actually seems to favor a state of ketosis. Compared to non-pregnant women, blood ketone concentrations are about 3-fold higher in healthy pregnant women after an overnight fast.[3] And in late pregnancy, metabolism shifts to a state of catabolism, making ketosis even more frequent.[4] Knowing this, I would expect that every pregnant woman experiences ketosis at some point during her pregnancy (particularly if she experiences nausea or food aversions!).
I find it hard to believe that our bodies would perpetuate a state of ketosis if it was truly harmful to a baby, but I continued my research into the topic. The majority of studies on ketosis are actually looking at diabetic ketoacidosis (DKA) or starvation ketosis, not nutritional ketosis (induced by eating a low amount of carbohydrates).
First, let me state that diabetic ketoacidosis is an extremely dangerous phenomenon, pregnant or not, that occurs in people with insulin dependent diabetes. This is classically due to skipping insulin shots, incorrectly dosing insulin, or taking inadequate insulin to cover unexpected elevations in blood sugar. Unlike nutritional ketosis or starvation ketosis, DKA is accompanied by unnaturally high levels of ketones from complete insulin deprivation and blood sugar levels at least three times higher than normal, which profoundly and dangerously alters the acid-base balance in the body. The blood sugar levels seen with DKA are themselves teratogenic (can cause birth defects), so this state should obviously be avoided by pregnant women. Some studies have suggested the metabolic effects of diabetic ketoacidosis may harm fetal brain development.[5]
However, to assume that all ketosis is harmful to a developing baby is illogical. For example, nutritional ketosis (the type of low level ketosis sometimes experienced on a low carbohydrate diet) is accompanied by normal blood sugar levels, blood ketones at very low levels (in general, thirty-fold less than what’s seen in diabetic ketoacidosis), and normal acid-base balance in the blood. So if a woman eats a lower carbohydrate diet during pregnancy, she might experience ketosis from time to time, but it’s not anywhere close to ketone levels induced by DKA in a pregnant woman with uncontrolled diabetes. Even if a woman tests positive for urinary ketones, it’s highly unlikely her blood ketone levels will be elevated. Studies on pregnant women who test positive for urine ketones rarely have detectable levels in the blood.[6]
So although the fetus requires glucose for growth, it also requires ketones. Either fuel provided in excess is harmful to the developing fetus, but as long as a mom is consuming enough calories and maintaining normal blood sugar levels, the baby will get just the right mix.
Given all of this information, I’ve changed my stance on the recommended carbohydrate levels for pregnant women and believe that it is safe to go low carb during pregnancy – at least lower than the arbitrary “minimum” of 175g per day suggested by most dietitians.
Now before you cut out all carbs, know that there are a variety of carbohydrate foods that pregnant women should continue to eat, including vegetables, fruit, nuts, seeds, and if they are tolerated, dairy and legumes. Eating fewer carbohydrates generally means women will eat less refined grains, junk foods, and added sugars, leaving more room for nutrient-dense foods that provide a growing baby with essential nutrients.
Many women do just fine eating a more moderate level of carbohydrates in pregnancy, so I do not believe everyone needs to goes low carb. But if you have medical conditions that are tied to blood sugar issues, such as gestational diabetes, preeclampsia, or you simply want to prevent excess weight gain, you should know it’s safe to eat a lower carbohydrate diet while pregnant.
*This article includes excerpts from Lily’s book, Real Food for Gestational Diabetes: An Effective Alternative to the Conventional Nutrition Approach, which includes an entire chapter exploring the research on ketosis during pregnancy.
About Lily:
Lily Nichols, RDN, CDE, CLT is one of the country’s most sought after ‘real food for pregnancy’ experts whose approach to nutrition embraces real food, integrative medicine, and mindful eating. You can learn more about Lily by visiting her popular blog, www.PilatesNutritionist.com and get her book, Real Food for Gestational Diabetes (and snag an exclusive FREE guide on managing gestational diabetes) at www.realfoodforGD.com.
References
[1] Mavropoulos, John C et al. “The effects of a low-carbohydrate, ketogenic diet on the polycystic ovary syndrome: a pilot study.” Nutr Metab (Lond) 2 (2005): 35.
[2] Metzger, BoydE et al. “” Accelerated starvation” and the skipped breakfast in late normal pregnancy.” The Lancet 319.8272 (1982): 588-592.
[3] Felig, Philip, and Vincent Lynch. “Starvation in human pregnancy: hypoglycemia, hypoinsulinemia, and hyperketonemia.” Science 170.3961 (1970): 990-992.
[4] Herrera, E. “Metabolic adaptations in pregnancy and their implications for the availability of substrates to the fetus.” European journal of clinical nutrition 54.1 (2000): S47.
[5] Rizzo, Thomas A et al. “Prenatal and perinatal influences on long-term psychomotor development in offspring of diabetic mothers.” American journal of obstetrics and gynecology 173.6 (1995): 1753-1758.
[6] Coetzee, EJ, WPU Jackson, and PA Berman. “Ketonuria in pregnancy—with special reference to calorie-restricted food intake in obese diabetics.” Diabetes 29.3 (1980): 177-181.
[7] Institute of Medicine (US). Panel on Micronutrients. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids. Panel on Macronutrients Panel on the Definition of Dietary Fiber, Subcommittee on Upper Reference Levels of Nutrients, Subcommittee on Interpretation and Uses of Dietary Reference Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board. National Academies Press, 2005.
[8] Bon, C et al. “[Feto-maternal metabolism in human normal pregnancies: study of 73 cases].” Annales de biologie clinique Dec. 2006: 609-619.
Alas, I’m not of an age to ever be pregnant again LOL ! I now enjoy my children and my grandchildren …….BUT I enjoyed reading this post.
Dr, Jay Wortman’s wife carried their daughter Izzy whilst on a low carb high fat lifestyle and Izzy is fantastic. My daughter in law carefully watched what she was eating whilst pregnant, and now the children (my grandchildren) do eat more of a LCHF lifestyle, although not to the same degree as myself, or Eddie do.
I’m sure all who read this post will find it very interesting – thanks.
All the best Jan
Thanks so much for your comments, Jan. I’ve never met Izzy but have heard many stories about what a bright and engaging child she is. So glad to hear that so many of your family members follow some form of carb-restricted way of eating, including the grandchildren!
Best regards,
Franziska
Thanks for the well written and researched article Lily, and thanks to Franziska for publishing it.
My daughter, who has blood sugar issues and treats them with carb restriction, is pregnant found this to be very useful info.
Thanks very much for commenting, Tim. I’m so glad to hear that your daughter is managing her blood glucose issues with LC during her pregnancy. Best wishes for good health to you, your daughter, and the rest of your family.
Excellent and timely article and comments about ketogenesis during pregnancy, as many young women adopting LCHF diets are in their fertile years.
I’m not one of those but am on the other end (70 y/o), have been on LC for over 5 years and recovered from metabolic syndrome.
I’m thrilled to have discovered Fransizka through the Carb Wars blog. I’m exploring lowcarbdietician blog for the first time this morning. I read extensively about metabolic syndrome, ketosis, LCHF and am so glad that useable, truthful, scientifically-backed information is finding its way out of the online miasma of misinformation.
Good luck Fransizka and bless you.
Welcome, Hazel! Thank you so much for all of the great comments and very supportive words! Congratulations on recovering from metabolic syndrome by adopting a low-carb approach. I’m so happy that you like my site.
Thanks very much again, and I hope you enjoy my future blog posts as well 🙂
I can never become pregnant but this was an interesting read. It could be very useful for first time mothers. Thanks for sharing!
You’re most welcome! Glad you enjoyed the post.
Thank you for writing this! I tend to have 10 & 11 lbs babies, although I have NEVER had gestational diabetes, I just allowed myself to gain too much weight (like 40-60 lbs typically). I was overweight when I got pregnant. This pregnancy, I fill my plate with 1 protein, 1 green vegetable, and 1 vegetable of any choice (and I get to add cheese), cooked in butter or coconut oil. I have only gained 4 lbs during this pregnancy and just started my third trimester. I look forward to AVOIDING another c-section due to “big baby” and I am enjoying this pregnancy more than any of the others!
Thanks so much for your comments, Robbi! Congratulations on following a whole-food, lower-carb approach this time around and gaining far less weight than with your previous two. I hope you have a wonderful third trimester, and best wishes for an easy delivery and healthy baby!
Just to update…. I followed the low glycemic diet during this pregnancy to avoid another c-section for a big baby. My babies have been 10 and 11 + lbs in the past. This baby was born full term at 7 lbs even. Very easy delivery, and no c-section!
That’s great news, Robbi! So glad to hear your baby was born healthy and you didn’t require a C-section. Congratulations on the newest addition to your family 🙂
Oh hooray, at last someone who provides info I can use. I’ve been on a low carb lifestyle for 2 years. Lost 70kg. As a result, also discovered just a month ago that I am pregnant – after more than 8 years of being told I am infertile. I guess losing that weight was a factor. So am very keen to stay low carb through my pregnancy. Thanks, very useful info.
Congrats on your fantastic weight loss and pregnancy, Kirsten! Best of luck to you!
After reading through this post I feel more confident in my decision to eat a low(er) carb and diet during my second pregnancy. I am only five weeks along, but pretty overweight. My weight caused issues such as high blood pressure and preeclampsia with my first pregnancy five years ago. I found the ketogenic diet over the past summer and followed it for three months, losing forty pounds and feelings fantastic, but with my birthday and thanksgiving, I fell off the wagon hard, gained around fifteen back and feel ultra crappy during these early weeks battling morning sickness. I’ll be reaffirming my commitment to low carb starting now, and trying to be as healthy as I can be for number two. Thanks for reading.
Thanks for your comments, Kasie. Wishing you a happy and healthy pregnancy!
Thank you for a well written and researched piece. As a practicing ob-gyn this is a great resource to show my patients.
Thanks for your kind words about Lily’s article, Maria. Thank you for sharing it with your patients.
Thanks so much for this article. I have had couple of 10lb babies ( gaining lots of weight myself) and when I got to my fifth, I was finally diagnosed with gestational diabetes. Struggled to keep my blood sugar levels low with the nutritionist advice about making sure I have enough carbs. Baby five was born about 9 lb.
Pregnant again with number six. This time I decided to just eat really good food and steer clear of high carb foods. Lost some weight during the first trimester ( The first pregnancy I haven’t gained about five KG during this time ) weight is remaining steady now during the second trimester. Feeling so good, and blood sugar is so easy to control now. Looking forward to an even smaller baby at birth this time, and much less baby fat to lose myself!
Thanks for relieving my fears about my enjoyably healthy diet. 🙂
Thanks for your comments and for sharing your story, Kat! I wish you the best of luck with your pregnancy and overall health.
Thank you SO much for this article!!! I am 24 weeks pregnant with my second, and had GD my first pregnancy and since this time I am planning for a home birth using a midwife I started testing my sugars early at 20 weeks and this last meeting with my midwife she told me I had ketones and that as it used to be something that they would worry about that they now know that it is not a concern. Despite her wisdom and advice I still wanted to look it up to make sure that she was correct. I found many many articles that spoke only about ketoacidosis and not many about low carb ketones in urine only, and those articles were not in relation to GD at all. Your article was a breath of fresh air and exactly what I needed to find. Thanks again.
Thanks for your kind words about Lily’s article, Ashley. I’m glad you found it helpful and reassuring. Best of luck with the rest of your pregnancy!
Great post! I have three children and all of them were difficult pregnancies and births. I started eating low carb long after they were all born and I’ve often wondered what difference there might have been with my pregnancies if I’d discovered low carb eating back then. 🙂
I found this interesting (and as a T1D who eats moderate-carb, i.e., under 100g/day and is TTC — encouraging), but unfortunately a lot of the references are rather old. I would be curious to see more recent studies dealing with these questions.
Thank you so much for this valuable information! I’ve been following a low carb diet for about 7 months and just found I’m over 3 weeks pregnant, so I had a lot of doubts about continuing with the diet. This clarifies a lot and makes me feel at ease with my eating style.