Overview

Whatever your long-term goals for weight or health, you have one priority when you are pregnant – to ensure you and your baby are healthy. What you eat plays a significant role in this. While a lot of research is available, there is no definitive evidence to support one ideal diet for everyone. There are many varying opinions on diet, and nutrition is very individualized. This article overviews popular diets and considerations for continuing or starting these diets during pregnancy. Learn about the risks and benefits of diets like caloric restriction, low glycemic, keto, plant-based, carnivore, paleo, low fat, the Louwen diet for pregnancy and birth, and intermittent fasting.

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Diet

By definition, diet is the kinds of food you habitually eat. We also know diet to mean a specific course of food you restrict yourself to, usually for medical reasons or to lose weight. Diets restrict calories, limit certain foods, or increase particular foods. There are many varying opinions on diet, and nutrition is very individualized. There is no definitive research to support one ideal diet for everyone. This article provides an overview of popular diets and considerations for continuing or starting these diets during pregnancy. Read on to learn about weight gain during pregnancy and the safety of diets like caloric restriction, low glycemic, keto, paleo, low fat, the Louwen diet for pregnancy and birth, and intermittent fasting.

The Limitations of Research on Diet and Nutrition 

Studies on the long-term effects of consuming any food are complicated because of many variables. If you increase your consumption of one food, you will likely decrease your consumption of something else. We do not know whether the change in health or disease is related to eating more of one food or less of another.

Another challenge with research on nutrition and diet is that most studies rely on questionnaires that require participants to self-report the foods they consume. The problem is that the reporting is typically not very accurate. On top of the challenges of having an evidence-based approach to the right diet, there is no one-size-fits-all. Everyone is different, and we have different dietary needs based on our genetic makeup, location, activity levels, health, and many other variables. 

Increased Nutrient Requirements in Pregnancy

During pregnancy, you have many increased requirements for nutrients and energy demands, plus you have to supply your baby with everything they need to grow. The foods you eat should be your primary source of all the vitamins and nutrients you and your baby need. You should also be taking a high-quality prenatal vitamin to fill in any gaps in nutrients that can happen with any diet.

Weight Gain During Pregnancy

Pregnancy involves weight gain, and your care provider uses this metric to measure your and your baby’s health. Excessive weight gain or not gaining enough weight during pregnancy is associated with low and high birth weights for newborns, preterm delivery, gestational diabetes, preeclampsia, cesarean birth, and postpartum hemorrhage. Your risk for these complications is lower if you gain a healthy amount of weight during your pregnancy. The foods you eat are the most significant contributors to weight gain and maintaining a healthy weight during pregnancy.

The American College of Obstetricians and Gynecologists adopts their guidelines on how much weight you should gain during pregnancy from the Institute of Medicine. ACOG recommends that practitioners determine a woman’s Body Mass Index (BMI) at the initial prenatal visit to counsel her on appropriate weight gain during pregnancy. BMI is a calculation of your weight in kilograms divided by your height in meters squared. You can use this calculator to determine your BMI.

The four BMI classifications are:

Underweight BMI <18.5 

Normal weight BMI 18.5-24.9 

Overweight BMI 25-29.9 

Obese BMI >30 

BMI isn’t a perfect gauge of your health, and this calculation has limits. While it estimates body fat, it can over or underestimate body fat if you have a muscular build or have lost muscle. 

If you are underweight, your care provider expects you to gain more and less if you are overweight. These ranges are for singleton pregnancies, and the weight ranges are higher if you are pregnant with twins. 

Underweight (BMI <18.5) 28-40 lbs 

Normal weight (18.5-24.9) 25-35 lbs 

Overweight (25-29.9) 15-25 lbs (6.8-11.3 kg)

Obese BMI (>30) 11-20 lbs 

According to ACOG, there have been some controversial reactions from some physicians who believe that the weight gain targets are too high, especially for overweight and obese women. Concerns have also been raised that the guidelines do not differentiate degrees of obesity, especially for morbidly obese women. The overall recommendation is that the guidelines from the Institute of Medicine provide a basis for practice. Individualized care and clinical judgment are necessary for managing the overweight or obese woman who gains (or wishes to gain) less weight than recommended but has an appropriately growing fetus. Balancing the risks of fetal growth (in the large-for-gestational-age fetus and the small-for-gestational-age fetus), obstetric complications, and maternal weight retention is essential but will remain challenging until research provides evidence to further refine the recommendations for gestational weight gain, especially among women with high degrees of obesity.

Stepping on the Scale

It is routine for care providers to ask you to step on a scale at the beginning of every prenatal appointment. This can give some pregnant mothers anxiety about whether they are gaining too much weight or not enough. Typically, you will weigh more at each appointment. Remember that the weight you gain when pregnant isn’t all just fat or weight in your belly. The following figures are estimates and averages, and every woman is different. This should give you some guidelines of where the weight you gain comes from. 

Breasts grow 1 to 3 pounds (0.5 to 1.4 kilograms) 

A larger uterus adds 2 pounds (0.9 kilograms) 

The placenta at birth is about 1.5 pounds (0.7 kilograms) 

2 pounds (0.9 kilograms) in amniotic fluid 

Increased blood volume adds 3 to 4 pounds (1.4 to 1.8 kilograms) 

The increased fluid volume contributes to another 2 to 3 pounds (0.9 to 1.4 kilograms) 

Fat stores add about 6 to 8 pounds (2.7 to 3.6 kilograms). 

By the end of your pregnancy, your baby weighs an average of 7 or 8 pounds (3 to 3.6 kilograms)

Weight Gain by Trimester

Weight gain is not linear throughout the whole nine months of your pregnancy. In the first trimester, you should only gain a few pounds. You should experience a steady, gradual weight gain throughout your pregnancy in the second and third trimesters. You can expect around one pound per week if you start underweight or at a normal weight and half a pound a week if you are overweight or obese. 

Weight Gain in the Real World

Even with these guidelines in place, most women are not gaining weight within the suggested ranges. One examining over 18,000 pregnancies found that just 25.8% of women gained weight within the recommended ranges, with 21.3% gaining less and 52.9% gaining above. This was across the board for all women regardless of their pre-pregnancy weight. 

Your Pregnancy Diet Goal

Whatever your long-term goals for weight or health, you have one priority when you are pregnant – to ensure you and your baby are healthy. Your diet plays a significant role in this. You know the guidelines and that most women are not gaining weight within those guidelines. Whether you are eating healthy now or need to clean up your diet, pregnancy is an excellent opportunity to focus on eating healthy and developing or maintaining healthy eating habits. That could mean counting calories, adding more fruits or veggies, or cutting sugar.

Calories

Calories measure the amount of energy in a food or drink. You take in calories from your diet and burn calories with all physical activity, from breathing and thinking to working out. When you consume more calories than you burn, your body stores those extra calories as fat; over time, this can cause weight gain. Calories can be a helpful tool, but not all calories are equal. One hundred calories in sugar do not affect you in the same way 100 calories in protein do.

Calorie Needs During Pregnancy

The standard adult needs about 2,000 calories per day. This figure varies depending on many factors, including age, sex, activity level, and whether you are pregnant or breastfeeding. You can use this calculator to find the daily nutrient recommendations for you. This tool is for healthcare professionals and provides a lot of information, including a breakdown of macronutrients (carbohydrates, protein, fat) and vitamins and minerals.

The American College of Obstetricians and Gynecologists states that no extra calories are needed in the first trimester if you are pregnant with a single baby. In the second trimester, you will need an additional 340 calories per day, and in the third trimester, about 450 extra calories a day.

Calorie Restriction Diets

Diets that restrict calories aim at weight loss since you reduce the number of calories you consume below the number you use for energy. If you consider reducing the calories you consume during pregnancy, discuss it with your doctor or midwife first. Pregnancy is a critical time for development, and your primary focus should be growing a healthy baby.

Some animal studies observed that rats on a calorie-restricted diet gained less weight during pregnancy. Researchers also measured alterations in endocannabinoid levels in offspring, which is involved in metabolic and behavioral programming. They found that the offspring of the rats on a calorie-restricted diet during pregnancy gained more weight later in life. Although a calorie restriction diet in pregnancy may lead to weight loss, there may be other considerations.

Low Carbohydrate, Low Sugar, and Keto Diets

Low carbohydrate diets like Atkins or South Beach aim to cut down on carbohydrates. Many people experience initial weight loss, appetite suppression, feel like they have more energy, and have improved health. Your body uses carbohydrates, in the form of glucose, for fuel. When you are very low on carbs, your body can use ketones for energy. The Keto diet nearly eliminates carbs, focusing on increasing your ketone levels and burning ketones for fuel.

Since low carbohydrate diets are also low in sugar, they are attractive for someone with gestational diabetes. A randomized controlled trial examined treating gestational diabetes with a low carbohydrate diet and found no difference in insulin requirements or pregnancy outcomes. This study compared a diet of 40% carbs vs. 55%. One published paper suggested that while carbohydrate restriction improves maternal glycemia, similar and potentially more favorable outcomes may be achieved by less-restrictive approaches that include an optimal mixture of higher-quality carbohydrates with lower glycemic index and lower fat. A less restrictive nutritional approach may ease the anxiety associated with the diagnosis and plan for therapy.

Another study proposed that an unbalanced maternal diet may create babies with higher cortisol levels. They took mothers instructed to avoid carbohydrate-rich foods and measured cortisol in their children nearly 30 years later. Of course, like most studies on diet, this assumes that the mothers followed the diet they were supposed to.

There is a difference between cutting down on carbohydrates and nearly eliminating them with a diet like keto. If you are considering a low-carb diet, please discuss it with your doctor or midwife. It may also be helpful to talk about your goals and why this diet appeals to you.

Even if you are not interested in reducing carbs, there are benefits to reducing sugar. Sugar is a broad term for many molecules that make foods and drinks sweet. Over the years, we have steadily increased the amount of sugar in our diets. Data shows that back in the 1970s, the average American consumed about 37 grams per day. Now that number is up to 55 grams per day. Children consume even more sugar, averaging 73 grams per day. Sugar is in just about every food and drink we consume.

How your body processes different types of sugar varies. Plus, during pregnancy, there are changes to the way your body reacts to and processes glucose. For more information on sugar and its effects on you and your baby, see this article.

Louwen Diet

Dr. Frank Louwen is the head of obstetrics and prenatal medicine at the Frankfurt University Hospital in Germany. Dr. Louwen created the Louwen diet, a low glycemic diet in the last several weeks of pregnancy for easier labor. He has published a lot of research on obesity, hypertensive disorders, and breech birth. Unfortunately, much of his work is in German, and I had difficulty finding any information from him as the source on the Louwen diet. The Louwen diet restricts high glycemic foods from week 32 until birth. The glycemic index is a value assigned to foods based on how quickly they increase your blood sugar (glucose). You can view a list of common foods and how they rank on the glycemic index here.

In articles online, you can find posts that the Louwen diet will make your labor easier, create a smaller baby, and result in a less painful birth. The idea behind the Louwen diet is that consuming high-glycemic foods increases your insulin levels, which can hinder the release of prostaglandins. Prostaglandins are released leading up to labor and help soften the cervix to prepare it for effacing and dilating. Synthetic prostaglandins like misoprostol (Cytotec) and dinoprostone ( Cervidil and Prepidil) can induce labor. Prostaglandins can also play a role in reducing pain. This is one of many things in the symphony of hormones during birth.

I could not locate any research explicitly looking at limiting foods high on the glycemic index in the last 6-8 weeks of pregnancy. If you want to read more about the Louwen diet, see this blog post. I also do not see a downside to doing this since limiting sugar will overall benefit your health. Restricting foods high on the glycemic index may rule out eating dates in the last few weeks, which some evidence shows may make for an easier labor.

Low-Fat Diets

In 2016 evidence showed that the sugar industry sponsored a research program in the 1960s and 1970s that cast doubt on the hazards of sugar while promoting fat as the dietary culprit in coronary heart disease. The sugar industry did not disclose its role in funding and directing this research. For decades fat was blamed for heart disease, and it was thought that eating fat would cause unhealthy weight gain. In recent years, strong arguments have been made that fat is not as bad as the health community has portrayed it. Some fats are good for you. You need fat from your diet, and it is an essential nutrient. However, there are different types of fat.

Trans fats are produced in small amounts naturally in the stomachs of ruminant animals like cows. These fats can also be artificially made in partially hydrogenated oils. As of January 1, 2020, the FDA banned artificial trans fats from partially hydrogenated oils in food by stripping them of the GRAS (generally recognized as safe) label.

Saturated fats come primarily from animal sources. These are usually solid at room temperature. Plant sources of saturated fats are coconut & palm oil.

Monounsaturated fats are in olive, peanut, and canola oils, avocados, almonds, pumpkin, and sesame seeds. These oils are typically liquid at room temperature, solid in the fridge, and oxidize in high heat.

Polyunsaturated fats include omega 3 and omega 6 oils. DHA, an omega 3s, is a major structural fat in the human brain and eyes. DHA represents about 97% of all omega-3 fats in the brain and 93% of all omega-3 fats in the retina. DHA is crucial for your baby’s development of their brain and retinas during the third trimester and up to 18 months of life. There is a pile of evidence to back up the need for omega 3s and DHA when pregnant.

American and Western diets contain many oils high in linoleic acid, an omega 6.  This is high in corn oil, soybean oil, safflower oil, cottonseed oil, and sunflower oil. Diets in many Western countries have a high ratio of Omega 6s to Omega 3s. The range in the US is between 10-25 times as much omega 6 as omega 3. The ratio should be more like 4 to 1 or even 1 to 1. The issue with this high ratio is that Omega 6s can impact your body’s ability to convert ALA to DHA and EPA. Plus, omega 6s can cause inflammation.

You already know you should strive to eat whole foods rather than processed foods. That is a great start to cut back on some of these oils and lower your intake of Omega 6s to get closer to that 4 to 1 or 1 to 1 ideal ratio.

The bottom line is that fat isn’t necessarily bad. Many foods that advertise as fat-free or low in fat have added sugars. You must go beyond the bold print on the front of the label and look at the ingredients or the nutrition facts label. If you aim to reduce the fat in your diet drastically, you will also miss out on the healthy fats you and your baby need.

Plant-Based Diets

People choose to eat a plant-based diet for many reasons, including environmental, ethical, or health reasons. Regardless of your reasons for eating a plant-based diet, there is no denying that many animal products are rich in vitamins and nutrients. You must get nutrients from other sources if you avoid meats, seafood, eggs, or dairy. While it is possible to eat a healthy diet that does not include animal products, you must be mindful to ensure you are getting the nutrients you and your baby need. See this article for an in-depth review of protein, vitamins, and nutrients to pay attention to on a plant-based diet.

Carnivore

On the opposite end of the spectrum from a plant-based diet is the carnivore diet. The carnivore diet focuses on mainly eating animal foods and, as a result, restricts carbohydrates. This diet can range from primarily eating animal-based foods to eliminating all plants and incorporating many organ meats. The carnivore diet has gained traction because many people find benefits like weight loss and increased energy. Many adherents also experience an improvement in autoimmune disease, which may result from the carnivore diet being an elimination diet that removes everything except animal products.

While it may sound wild to eliminate plants from your diet, there are proponents like Dr. Paul Saladino who make a good case for eating carnivore. Interestingly, many proponents of this diet, like Dr. Saladino, have changed their stance in recent years to include fruits and animal products.

There is no research on the carnivore diet and pregnancy. It is possible to get all of the vitamins and nutrients you need from only animal products if you include nutrient-rich organ meats. Plus, the quality of meat matters, and a grass-fed steak is different from a hotdog. The carnivore diet is the most restrictive diet discussed in this article. Please do your research and talk to your doctor or midwife to ensure you meet all your nutrient requirements. See this episode for more information on eating meat during pregnancy.

Paleo Diet

The paleo diet focuses on foods that would have been available during the Paleolithic era, from about 2.5 million to 10,000 years ago. This diet eliminates all processed foods and foods that were not consumed by our ancestors, like dairy, legumes, and grains. This is touted as a good diet for weight loss, which, remember, should not be your primary goal during pregnancy. There are obvious benefits to cutting out sugar and processed foods, which the paleo diet does. I could not locate any research specific to the paleo diet and pregnancy.

Intermittent Fasting

Intermittent fasting is limiting your food intake to a shortened window. For example, you could eat in an eight-hour window between 9:00 am and 5:00 pm, then fast for 16 hours. Typically, there is no restriction on what you eat during your feeding window. You can and should drink water or zero-calorie beverages like tea when fasting. There is a lot of evidence that intermittent fasting improves glucose regulation, increases stress resistance, and suppresses inflammation.

A systematic review and meta-analysis looked at the research of pregnant mothers who fasted for Ramadan. This is a month-long period when Muslims fast from sunrise to sunset. Interestingly, expectant mothers are exempt from this practice, although many do participate. This included 22 studies of 31,374 pregnancies, of which 18,920 were exposed to Ramadan fasting. The researchers found that Ramadan fasting does not adversely affect birth weight, although there is insufficient evidence regarding potential effects on other perinatal outcomes. Further studies are needed to accurately determine whether Ramadan fasting is associated with adverse maternal or neonatal outcomes.

Remember that this was only for intermittent fasting for one month or shorter, not for the length of a pregnancy. Lily Nichols has a great post with a lot of evidence on why intermittent fasting is a mismatch for pregnancy. If you are considering intermittent fasting, please read her well-researched thoughts.

Cutting Through the Clutter

A study titled “Low carbohydrate diets may increase risk of neural tube defects” sent many low-carb fans into a panic that their diet could cause congenital disabilities. These headlines aim to get clicks, not deliver what this study found. Chris Kresser has a great article breaking down this study and pinpointing that it was more likely a lack of folate than low-carb that caused the neural tube defects. You know you need adequate folate, and you should be getting that from your diet and a high-quality prenatal vitamin.

 

Another example of this can be found in a study on the DASH (Dietary Approaches to Stop Hypertension) diet. This diet emphasizes eating more fruits, vegetables, whole grains, nuts, and lean protein. A study of overweight and obese women split the participants into two groups: coaching on the DASH diet and physical activity and the control group without coaching. Researchers measured weight gain and concluded that those in the intervention group gained significantly less weight. There were no significant differences in adverse pregnancy outcomes but more cesarean births in the group that received the coaching. While this study found statistically significant differences in weight gain, it amounted to five pounds or less over the course of pregnancy.

Every day a new click-bait headline pops up with the “19 Best Foods for Pregnancy” or ”Pregnancy week-by-week meal plans.” There will always be hype around diets; if there were one perfect diet for everyone, we would all be on it.

Eating Real Food

The closest thing to a perfect diet is to eat healthy whole foods. The bulk of your diet should be foods that were alive, whether this is plants or animals. You should be limiting processed foods. It is probably processed if it has a long ingredient list or things that you cannot pronounce or have never heard of. “Real food,” as Lily Nichols, RDN, CDE, puts it in her book, Real Food for Pregnancy. She writes, “In a nutshell, real food is made with simple ingredients that are as close to nature as possible and not processed in a way that removes nutrients.” I highly recommend her book if you want an evidence-based deep dive into what you should eat during pregnancy.

Diet Tips

There are simple tips to steer your diet in the right direction during pregnancy and beyond. These are fundamental concepts that anyone can and should apply to their diet. Although opinions on diet are constantly evolving, these tips are evidence-based on the current science.

Limiting sugar is always a good idea. If you can eliminate sugar entirely, great, but the keyword here is limiting. It is okay to enjoy dessert or sweets occasionally.

A good measurement of how well you are eating is how you feel. That said, pregnancy can come with fatigue and nausea that have nothing to do with your diet. Plus, eating a wide variety of foods can be challenging if you are experiencing morning sickness. While you may enjoy the taste of an unhealthy meal, you may not love how it makes you feel afterward. Take stock of how you feel after eating certain foods. You can use that feedback to steer your diet towards foods that leave you feeling satisfied and healthy.

During pregnancy, do not focus on weight loss; focus on eating well. If you are continuing or trying a specific diet, ask yourself what your goal is. If the primary goal is weight loss, it may not be a great fit during pregnancy. Talk to your doctor or midwife about any diet that is restrictive with a macronutrient, like carbohydrates or fats, or that restricts calories.

Food Cravings, Cheat Meals, and Treats

Many expecting mothers experience different food cravings during pregnancy. There is some speculation that if you crave a particular type of food, your body is trying to balance a nutrient deficiency. For example, if you are craving oranges, you need more vitamin C. Research doesn’t support that theory, and food cravings are likely psychological. You can indulge in food cravings that are not the healthiest options, just do not overdo it.

If your diet is too restrictive, it can be challenging to stick to it. Do not beat yourself up if you enjoy a meal outside of your diet or that is not healthy. You can eat relatively well and occasionally stray to enjoy a sugary treat or an unhealthy meal. It takes time to build healthy eating habits and work towards eating primarily healthy whole foods.

How to make Eating Healthy Easier

You can do many simple things to make eating healthily more accessible and more of a habit than a chore. Here are some tips to make it easier:

Meal plan before grocery shopping so you don’t buy foods you want to avoid.

If you have trouble sticking to a list or don’t like reading labels at the store, try shopping online and getting your groceries delivered.

It can be time-consuming to cook meals from scratch. You can save time if you batch meal prep and cook by making several meals or servings at once.

If you can’t stand a particular food, don’t eat it. It does not matter how healthy something is; skip it if you do not enjoy eating it. There are so many options. With some experimentation, you can find healthy foods you love to eat.

Keeping a food journal is A powerful tool for ensuring you are eating well. You don’t have to do this for your entire pregnancy. Even keeping track of meals for a week and reviewing what you eat can help pinpoint where you can improve.

It takes time to make eating a healthy diet a habit. Plus, there can be a big learning curve to know what foods are good and which you should avoid. It can be daunting at first if you are new to reading nutrition labels. Over time, this does get easier. The time you spend upfront will pay off in the long run.

Eating Disorders

The diet industry is a $40 billion per year industry. Diet companies gear marketing towards making you feel like you have to go on a diet to fit some standard of what your body should look like. 9.2% of women pre-pregnancy and 7.5% of pregnant women have an eating disorder. These figures are for disorders that are clinically diagnosed. Many individuals may have an unhealthy relationship with food even though they may not be clinically diagnosed with an eating disorder. Some good news: those with an eating disorder before getting pregnant generally tend to improve during pregnancy. That doesn’t mean it is easy or they do not struggle. Remember that pregnancy can cause past easing disorders to resurface, causing relapse.

If you have any questions about eating disorders or negative habits around eating, please bring them up with your doctor or midwife. If you have dealt with an eating disorder in the past, or are currently dealing with one, talk to your care provider. You may also consider seeking a midwife or OBGYN who has experience with patients who have had eating disorders. You need to know that you are not alone in this struggle and that there are resources to help. A great start is to talk to your doctor or midwife. You can learn more about eating disorders during pregnancy in the episode on Body Image.

Talk to Your Doctor or Midwife

In 1985, the National Research Council’s Committee on Nutrition in Medical Education recommended  25 hours of nutrition education in medical school. This recommendation should likely be increased based on what we have learned about nutrition and diet over the past four decades. Plus, add many years between medical school and practice; some of the learned information may be outdated. Despite the long-standing 25-hour recommendation, most medical students are not receiving adequate education in this area. According to one report that surveyed 121 medical schools in the United States, 71% do not meet the 25-hour recommendation. 36% provide less than half of that. The lack of education in diet and nutrition is not just a problem in the United States. A systematic review of 24 studies found that medical students are not receiving adequate nutrition education worldwide.

Even though most schools lack sufficient education, some medical professionals independently educate themselves about diet and nutrition.

Hopefully, your care provider is knowledgeable and up-to-date on nutrients, vitamins, and diet. If you have questions about your diet or whether you are meeting the requirements for nutrients you and your baby need, please talk to your doctor or midwife. If you are not getting sufficient answers to your questions, you may need to consult a dietician or do your research to advocate for yourself. If you are concerned that you are deficient in vitamins or nutrients, you can always request a blood panel.

Additional Resources

Many additional episodes of the Pregnancy Podcast dive into detail on specific aspects of diet and nutrition. Consider exploring the following episodes for more in-depth information.

• Hydration and Drinking Water
• Protein During Pregnancy and Supplementing with Protein Powder
• Plant-Based Diets During Pregnancy
• Eating Organic During Pregnancy
• Eating Meat During Pregnancy
• Eating Fish During Pregnancy
• Drinking Tea During Pregnancy
• Kombucha
• Sushi
• Sugar
• Natural and Artificial Sweeteners
• What to Look for in a Prenatal Vitamin
• Omega 3 and Fish Oil Supplements During Pregnancy
• The Evidence on Vitamin D
• Iron During Pregnancy and Breastfeeding
• Probiotics

Thank you to the amazing companies that have supported this episode.