The keto — short for ketogenic — diet (KD) is a nutrition trend that has been advertised as a “miracle diet” and as a healthy eating plan for fixing, well, nearly everything.

There’s no doubt that most Americans — even pregnant ones — probably need to eat fewer simple carbs and less sugar. But you may wonder if the keto diet — which is a high fat, very low carb eating plan — is safe during pregnancy.

We know you’re trying to be healthy while you’re “eating for two” (though don’t do this literally). Kudos to you! But is pregnancy the right time to be on the keto diet — or any trendy diet, for that matter?

You’re right to question this: Eating a balanced diet is even more important when you’re pregnant. Your growing body and baby need a variety of colorful foods to use as fuel and building blocks.

Let’s take a closer look at keto and pregnancy.

On the keto diet, you’re typically allowed lots of meat and fat, but less than 50 grams (g) of carbs a day — that’s about one all-seasonings bagel or two bananas in 24 hours!

The diet also has an unusually high fat requirement. This means that in a 2,000 calorie-a-day keto diet, each meal might have:

  • 165 g fat
  • 40 g carbohydrates
  • 75 g protein

The idea behind the keto diet is that getting most of your calories from fat jumpstarts your body’s natural fat-burning. (Carbohydrates are easier for the body to use as fuel. When you eat plenty of carbs, they’re used for energy first.)

A keto diet is supposed to help shift your body from burning carbs to burning fat for energy. This state is called ketosis. Burning more fats for energy may help you lose weight — at least in the short term. Simple, right?

Reaching the fat-burning state (ketosis) isn’t as simple as it sounds. Even if you’re not pregnant, it can be difficult to follow the keto diet correctly, or even know if you’re in ketosis.

Carbs are a huge no-no in this diet — including fruits and most vegetables, which have natural sugars. Eating too many can give you more carbs than keto allows. Just 1 cup of broccoli has about 6 g carbs, for example.

But pregnant women need brightly colored fruits and vegetables — rich in vitamins, iron, and folate — to nourish their growing baby. Vegetables also have fiber — a known possible deficiency while on keto — that can help with pregnancy constipation.

In fact, some nutrition experts recommend that anyone on a keto diet should take supplements.

If you’re eating a keto diet you might have low levels of:

  • magnesium
  • B vitamins
  • vitamin A
  • vitamin C
  • vitamin D
  • vitamin E

A prenatal vitamin — a necessity during pregnancy — does provide extra nutrients. But it’s best to get these vitamins and minerals in foods, too. During pregnancy you need even higher doses of these nutrients as you and your baby grow rapidly.

Not getting enough of some vitamins and minerals can lead to problems in your baby’s growth and development. Vital nutrients for your baby include:

  • vitamin D for healthy bones and teeth
  • vitamin E for healthy muscles and blood
  • vitamin B-12 for healthy spinal cord and nerves
  • folic acid for a healthy spinal cord (and also to prevent a neural tube condition in babies called spina bifida)

Protein is part of the keto diet, but most keto diets don’t differentiate between healthy, lean protein and the kinds with lots of saturated fats like beef and pork. In fact, since fat is so encouraged, the diet can actually lead people to eat more unhealthy meat — as well as oils, butter, and lard.

Make no mistake: Healthy fats are essential for your growing baby. But too much saturated fat can cause health problems like higher cholesterol for you, which puts a strain on your heart and therefore your pregnancy.

The keto diet also doesn’t stop you from eating processed sandwich meats like hot dogs, bacon, sausages, and salami. These meats have added chemicals and colors that may not be healthy for your tiny, growing baby — or for your body.

For some people, the keto diet causes so many side effects that they even have a name for it. The “keto flu” includes side effects like:

  • fatigue
  • dizziness
  • nausea
  • vomiting
  • dehydration
  • bloating
  • stomach pain
  • gassiness
  • constipation
  • diarrhea
  • high cholesterol
  • headaches
  • bad breath
  • muscle cramps

Pregnancy comes with its own (very normal) side effects, which can include nausea, vomiting, tiredness, stuffy nose, and aches. You definitely don’t need to add the keto flu or uncomfortable stomach symptoms to this!

It’s not usually considered ethical to use pregnant women as subjects in clinical studies because of the risks. So medical research on the keto diet during pregnancy has mostly been done on animals like mice.

One such 2013 study showed that pregnant mice that were fed a keto diet gave birth to baby mice that had a larger heart and smaller brain than typical.

A 2015 study found that pregnant mice on a keto diet had babies that had a higher risk of anxiety and depression when they became adult mice.

People aren’t mice (clearly), and it’s not known if the keto diet would have the same effect on pregnant women and their babies.

The keto diet may be one way to help treat people with epilepsy. This brain condition causes people to sometimes have seizures. And a 2017 case study found that the keto diet might help control symptoms in pregnant women with epilepsy.

Case studies are often tiny — with just one or two participants. In this case, the researchers followed two pregnant women with epilepsy. The keto diet helped to treat their condition. Both women had normal, healthy pregnancies and delivered healthy babies. The women’s only side effects were slightly low vitamin levels and raised cholesterol levels.

This isn’t enough evidence to say that the keto diet is safe for all women during pregnancy. More studies are also needed on how the keto diet helps people with epilepsy and other health condition.

Gestational diabetes is a kind of diabetes that women can get during pregnancy. It usually goes away after the birth of your baby. But it can increase your chances of getting type 2 diabetes later on.

Gestational diabetes can even raise the risk that your baby gets diabetes later on in life. Your doctor will give you regular blood sugar tests to make sure you don’t have gestational diabetes.

Some case studies, such as this one from 2014, show that a keto diet can help manage or prevent some kinds of diabetes. However, you don’t have to go full keto to lower your risk of gestational diabetes. Eating a low carb diet that has plenty of healthy fat, protein, fiber, fresh fruit, and vegetables is a safer bet while you’re pregnant.

It’s also vital to get moving — 20 minutes of exercise after each meal can also help you balance your blood sugar levels during and after pregnancy.

Some articles and blogs claim that the keto diet can help you get pregnant. This is thought to be because going keto can help some people balance their weight.

If you’ve been told by your doctor that you need to lose weight, doing so may help improve your chances of getting pregnant. However, there’s not yet medical evidence that shows that the keto diet can boost fertility.

And if you’re trying to get pregnant, the keto diet might actually slow things down. Several vitamins and minerals can help make men and women more fertile. Being on a keto diet might lower the levels of nutrients that are important for fertility. According to medical research, these include:

  • vitamin B-6
  • vitamin C
  • vitamin D
  • vitamin E
  • folate
  • iodine
  • selenium
  • iron
  • DHA

Eating a balanced diet with plenty of fruit, vegetables, whole grains, and healthy fats and protein is very important during pregnancy. The keto diet may not be a good option while you’re pregnant because it can prevent you from eating lots of nutrient-dense foods. This includes fresh, dried, and cooked fruits and vegetables.

More research is needed, and new studies may change the medical community’s opinion on keto while pregnant. Regardless, we recommend checking with your doctor or nutritionist before starting any kind of diet whether you’re planning or expecting a child or not — but especially when you’re pregnant.

A good rule of thumb is to eat the rainbow — and yes, that can even include pickles and Neapolitan ice cream (in moderation!) when cravings call for it.