Are the Fad Diets Safe for Pregnancy

Summary: Everyone has read those magazines at some point that claim they have “the best diet to help you lose 20 pounds and look your best!” While these claims seem illustrious and worth trying, the science behind many is unfounded and may actually lead to nutrient deficiencies and health problems.

What are Fad diets?

Most fad diets become popular for a short time and usually make claims such as fast weight loss. When it comes to “diets,” in general there seems to be the assumption that it is short-term. This is one reason fad diets fall short. The other reason fad diets may not be the best choice is that some of them may restrict certain foods or entire food groups, which may lead to deficiencies during pregnancy. 

Whatever eating style you choose, we highly recommend speaking to an expert and maintaining a well-balanced diet rather than following a fad diet regimen. That being said, here are some examples of diets you may have heard about.

Low Carbohydrate Diets

• Ketogenic diet: With the ketogenic diet, the body is deprived of most carbohydrates, increasing fat intake, and eating moderate amounts of protein. This forces the body to utilize fat as it’s the main fuel source. There is not sufficient research to suggest the keto diet is completely safe during pregnancy.

One study completed on pregnant mice found that embryos had larger hearts and smaller brains when the mothers were fed a keto diet. Another study found that adult mice whose mothers were fed a ketogenic diet during gestation were more prone to hyperactivity, anxiety, and depression. Now, humans are not mice and the micronutrient profile of these diets were not provided. There were likely many nutrients that were missing in the keto diet given to these mice, which could be added in when actually planning meals ...hard to say for sure. 

Another study found that women who followed a low carbohydrate diet in the year before conception had an increased risk of neural tube defects due to lower folate and folic acid intake. This study however, put emphasis on carbohydrate sources fortified with folic acid, which is not necessarily the best choice for folate intake (we discuss this in our All about Folate article). Regardless, their results show that some low carb diets may be severely lacking in certain nutrients.

• Atkins: The Atkins diet also prioritizes a diet low in carbohydrates. There are multiple phases with different suggested amounts of carbohydrate restrictions. On their website, if you choose that you are breastfeeding or pregnant when taking their quiz to determine your plan, they suggest the least restrictive. Their least restrictive plan encourages 6 to 8 servings of vegetables and 3-5 servings of other carbohydrates, which seems safe and likely a lot more veggies than most Americans are eating. However, as with many of the fad diets there's very little research in relation to pregnancy. 

Takeaway message: We do not recommend extremely restrictive diets. However, if your idea of lower carbohydrate intake is cutting back on refined grains, junk food, foods with added sugars, sodas, then by all means continue to limit these foods. Limiting these foods can help with blood sugar control and weight gain. There are mixed research findings on lower carbohydrate diets and the need for insulin, but monitoring your carbohydrate intake each meal/snack and pairing them with protein or fat can help blood sugar control. 

The issue we have is that if you restrict carbohydrates too much, you are missing valuable nutrients from foods like vegetables, fruits, whole grains, legumes, and dairy (if you can tolerate dairy). 

Specific Food Group Diets 

• Paleo diet: The paleo diet is an attempt to recreate the diet that early humans ate which most likely included fish, animal meat, fruits and vegetables, nuts, and other whole foods, excluding grains, legumes, dairy, refined sugar, and processed oils. One small study found that the paleo diet had beneficial effects on glucose tolerance, iron stores, and hemoglobin levels. 

• Whole 30: The whole 30 diet emphasizes eating whole foods (similar to paleo) and elimination of refined sugar, legumes, grains, and dairy. This diet does not support snacking, which may be necessary during pregnancy to eat enough calories or to support blood sugar (think small meals throughout the day). This diet lacks research in regards to the effects of the diet on maternal and fetal health. That being said, there are benefits to eliminating food additives and added sugar and focusing on whole foods. It will be important for you to listen to your body, ensuring you eat enough of the foods you and your baby need. 

• Mediterranean: The Mediterranean diet includes vegetables, nuts, legumes, whole grains, fish, fruits, limited amounts of red meat, and unsaturated fats. This diet is perhaps one of the more substantiated diets supported by research and indicates that this diet is safe for both maternal and fetal health. 

Thoughts about Fad diets

Personally, we don’t like the word diet. Eating should not be stressful, but our society puts a lot of pressure on eating certain foods and being as skinny as we can be --- this is NOT real life. While some of the above-mentioned eating styles may be beneficial to you and your baby’s health, there is no one-size-fits-all eating style. 

Eating a variety of nutrient-dense foods is beneficial to you and your baby. This may take some strategic planning, but we are here to help! We try our best to provide you with information you can use to plan your meals in a way that fits your own needs.

That being said, your eating style is your choice. If you choose to follow a specific “diet,” be honest and open with your healthcare provider. If you have diet-specific questions, check out our “ask us anything” Instagram posts. Your questions will be answered by our in-house Registered Dietitian. 

References

Sussman, D., van Eede, M., Wong, M. D., Adamson, S. L., & Henkelman, M. (2013, May 8). Effects of a ketogenic diet during pregnancy on embryonic growth in the mouse. BMC pregnancy and childbirth. Retrieved November 20, 2021, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3685567/. 

Masood, W. (2021, August 22). Ketogenic diet. StatPearls [Internet]. Retrieved November 20, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK499830/. 

Sussman, D., Ellegood, J., & Henkelman, M. (2013, October 29). A gestational ketogenic diet alters maternal metabolic status as well as offspring physiological growth and brain structure in the neonatal mouse. BMC Pregnancy and Childbirth. Retrieved November 20, 2021, from https://link.springer.com/article/10.1186/1471-2393-13-198. 

S; LMLIM. Paleolithic diet during pregnancy-a potential beneficial effect on metabolic indices and birth weight. European journal of obstetrics, gynecology, and reproductive biology. https://pubmed.ncbi.nlm.nih.gov/31522093/. Accessed December 1, 2021. 

Moreno-Castilla C, Hernandez M, Bergua M, et al. Low-carbohydrate diet for the treatment of gestational diabetes mellitus: A randomized controlled trial. Diabetes care. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3714525/. Published August 2013. Accessed December 1, 2021. 

Amati F, Hassounah S, Swaka A. The impact of Mediterranean dietary patterns during pregnancy on maternal and offspring health. Nutrients. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566342/. Published May 17, 2019. Accessed December 1, 2021.