Keto is all the rage right now. It’s no surprise when it is asked if ketogenic diets are safe during pregnancy. While it can be helpful in improving fertility health, is that same approach appropriate for pregnancy?
What is keto?
The ketogenic diet is an approach to a metabolic state in which the body relies on fats for fuel. This happens by consuming very low carbohydrates (usually between 25-50 grams of carbs), with a high intake of fats. As a rough estimate, a ketogenic diet follows about 70-80% calories from fats, 20-25% from protein, and 5-10% from calories.
The body, even though typically prefers glucose as primary fuel, does naturally go into states of ketosis, including during pregnancy. In fact, according to Lily Nichols in her book, Real Food for Pregnancy,
Nutritional ketosis is more common in women who eat a diet limited in carbohydrates, and you’re most likely to have ketones in your urine when you’re fasted (first thing in the morning) or when it’s been a long time since you last ate. Pregnant women naturally have urine ketone levels 3-fold higher than non-pregnant women after an overnight fast.
Confusion Surrounding Ketosis
Ketosis vs Ketoacidosis
A common fear surrounding a ketosis state during pregnancy is that there may be harm to the fetus, particularly to the brain. When this fear comes up, it’s possible they’re actually referring to the state of diabetic ketoacidosis. Diabetic ketoacidosis (DKA) is, in fact, a harmful state for anyone to be in, pregnant or not. DKA is a state usually occurring in those with mismanaged diabetes.
The main difference between ketosis and DKA is the level of ketones found in the blood, which is not the same as ketones found in the urine, such as with a urine test at a prenatal checkup. High amounts of ketones found in the urine is not always indicative of high amounts of ketones in the blood. (It certainly can be, but testing the actual blood ketones would be the only way to tell.) With DKA, the ketones in the blood is extremely high. This can lead to acidic blood, and may even be fatal if left untreated.
Ketosis vs Starvation
Ketosis is also sometimes referred to as a state of starvation. That statement is a bit misleading when ketosis is done properly. In a state of starvation, the body will pull from the muscle stores in an effort to fuel the body, which then leads to a decreased muscle mass. While diabetic ketoacidosis can occur BECAUSE of starvation and lack of sufficient calories, it doesn’t necessarily mean the body is in a starvation mode just because it’s relying on fat instead of glucose. As long as sufficient calories are coming in, the body should not go into a “starvation mode”.
Conventional Nutrition vs Keto Diet
In comparison to the conventional nutrition recommendations during pregnancy, keto is quite an opposite way of eating. Higher carbohydrate intake (about 45-65% of calories, or about 250 grams on a 2200 daily caloric intake), low fat, and half grains being whole (taking into account that half grains can be refined) make up the conventional nutrition recommendations for pregnancy. As far carbohydrates, specifically, the Institute of Medicine recommends a minimum of 175 grams per day during pregnancy to ensure the fetus has proper glucose for fetal development and other energy needs are met. The ketogenic diet, as mentioned earlier, recommends fat being the highest intake, distantly followed by protein, and carbohydrates making up the least percentage of calories.
On the ketogenic diet, the typical protein standard is about 20% of calories. The recommended intake during pregnancy falls in the range of 20-30%. On a 2400 calorie diet, this would equate to a minimum of roughly 120 grams per day. Protein needs do change throughout pregnancy. In the first half of pregnancy, it’d be best to get at least 80-90 grams of protein per day, while later pregnancy protein demands are a little higher, closer to a minimum of 100 grams. Research has shown that both too much protein and too little protein can have an adverse effect on pregnancy and the developing baby. It’s important to listen to your body here.
It’s certainly possible to consume an adequate and safe amount of protein on the keto diet. Ideally, include a variety of protein sources in the daily diet to ensure a good balance of nutrients.
As mentioned earlier, the highest consumption on the ketogenic diet is fat. Roughly 70-80% of calories should be coming from fat while following keto. This is quite opposite from conventional prenatal nutrition, that advises to limit overall fat intake. Healthy fats, however, are a very necessary part of pregnancy health and fetal development rather than being something to fear. The only fats that should be limited or avoided are trans fats, and highly processed fats like canola, vegetable oil, soybean and cottonseed.
Carbohydrate intake on the ketogenic diet is very low. This, in my opinion, is the biggest part of the ketogenic diet to really take into consideration. A very low carbohydrate intake, as with keto, might not be able to provide the essential micronutrients needed for fetal development and pregnancy health. Animal studies suggest insufficient carbohydrate intake can negatively affect fetal growth. There are certain needs to be met during pregnancy, for example at least 33 grams a day of carbohydrates alone are necessary for fetal brain health, as per Lily Nichols. On the keto diet, a typical carbohydrate intake falls between 25-50 grams of carbohydrates, meaning between fetal requirements not being met to not much being left for you.
Carbohydrates are also necessary for thyroid health, specifically for converting the hormone T4 to T3. During the first half of pregnancy, the fetus completely depends on your own thyroid function. After that, thyroid hormones continue to be passed through the placenta and play a part in the baby’s development.
Carbohydrate intake should come from whole foods as often as possible, both starchy and non-starchy vegetables, fruits, beans, and legumes. Processed foods like bread or cereal, even if fortified, wouldn’t be providing the same quality nutrients.
Is low-carb right for YOUR pregnancy?
Did you follow a low-carb lifestyle prior to pregnancy?
This is a question to be very honest about with your answer. Without already being “fat-adapted”, a sudden switch as dramatic as the ketogenic diet may be too stressful during pregnancy. It may be more beneficial to follow a lowER carbohydrate diet (and highER fat), but not quite keto.
Is your thyroid in good health entering pregnancy?
If you have hormonal imbalances or enter pregnancy with a thyroid condition, going very low carb may be a mistake. The thyroid depends on carbohydrates for thyroid hormone conversion. Without adequate carbohydrates coming in, thyroid health may end up suffering, which can be a problem during and after pregnancy.
Are you willing and able to track your ketone levels, fat grams, carbohydrate grams, and protein grams?
Tracking intakes is a key factor in ketogenic success and safety, especially during pregnancy. According to Lily Nichols’ research through the Dietary Reference Intakes from the Institute of Medicine in 2005, the minimum number of carbohydrates required for fetal development is, as mentioned above, 33 grams. It’s important to note that these carbohydrates are providing the very necessary glucose along with micronutrients so this number refers to unrefined carbohydrates such as vegetables. The micronutrients would not be provided by foods like bread.
Calorie intake is important on keto during pregnancy as well. If this low carb diet turns into low carb/low calorie, that can end up being a dangerous scenario.
Will you be able to make sure you consume enough micronutrients?
Micronutrients like vitamins and minerals are extremely important during pregnancy for proper fetal development. Going too low carb can leave you missing out on micronutrients like vitamin C, folate, and iodine.
Are you at risk for gestational diabetes?
In the first trimester, a hemoglobin A1c test will tell your blood sugar levels over the last three months. This test is an excellent predictor of gestational diabetes. If your A1c level is 5.7% or higher in the first trimester, you have a family history of gestational diabetes (GD) or diabetes, or have experienced GD in previous pregnancies, it may be a good idea to transition to a lower-carb diet as soon as possible, even better if prior to pregnancy, as well as monitoring your blood sugar regularly.
My General Recommendation
A very low carb diet may or may not be advised during your pregnancy. In my general opinion, it’s not quite worth the risk of following a very low carb lifestyle during pregnancy. Unless you’re at risk for GD, I believe it’d be safer to follow a lower carbohydrate/moderate healthy fat approach. Think of it like a happy medium between the conventional nutrition recommendations and the ketogenic diet. This might look more like 30-40% unrefined real food carbohydrate, 20-30% protein (from a variety of sources to include both plant and animal), and 40-50% healthy fats. However, I’d highly encourage any pregnant woman to eat more mindfully and not quite so “prescriptively”. There may be times when she wants more carbs, like to help that first trimester nausea.