Weight loss during pregnancy: is it safe?

Pregnancy has often been thought of as the time of a woman’s life when weight gain was not only acceptable but encouraged. It’s often referred to as “eating for two,” though this is not really an accurate description of the nutrition needed during pregnancy. 

Healthy weight gain during pregnancy is often encouraged for most women, but there are instances where weight loss during pregnancy is acceptable. This article will review when weight loss may be encouraged, how to do it safely, and what to know about unintentional weight loss during pregnancy.  

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For some, losing weight while pregnant can be dangerous, but for others, it may be safe and encouraged. It’s important to remember that each pregnant person needs to discuss their own particular weight goals with their healthcare provider.

Extra calories are generally needed as pregnancy progresses, with more calories required as the baby grows and to support the other tissues involved in pregnancy, such as the placenta and amniotic fluid. These calories also help the body prepare for delivery and breastfeeding by storing energy. Most of the increased calorie intake should occur during the second and third trimesters (Mousa, 2019).

Losing weight while pregnant can be intentional, particularly in those who experienced obesity pre-pregnancy. Weight loss during pregnancy can also be unintentional, especially if conditions make it difficult to eat. 

For unintentional weight loss, morning sickness is often the cause, especially in early pregnancy.  Although it’s a misnomer, morning sickness can last throughout the day, and it may prevent women from being able to eat or drink adequate calories due to nausea and vomiting. Morning sickness typically improves during the second trimester. 

A more severe form of sickness during pregnancy, called hyperemesis gravidarum (HG), can lead to significant amounts of unintentional weight loss (>5% of body weight) during pregnancy. It is much more than just severe morning sickness. People with this condition may experience extreme nausea and vomiting throughout the day. They often require hospitalization to control their symptoms with intravenous fluids and medications, allowing them to get the calories and nutrients they need for a healthy pregnancy (National Organization for Rare Disorders, 2020).

There can be some instances when it makes sense to try to lose weight while pregnant. Women who had obesity before pregnancy or who have excess weight during pregnancy are at risk of complications. These complications can include (Farpour-Lambert, 2018):

• Gestational diabetes

• High blood pressure

• Pre-eclampsia

• Preterm birth

• Stillbirth

• Having a baby with a high birth weight

You should thoroughly discuss any attempt at weight loss during pregnancy with your healthcare provider to develop the safest plan. The amount of weight loss recommended during pregnancy is an individual decision between the pregnant woman and her healthcare team (Farpour-Lambert, 2018).  

Losing weight during pregnancy may be done safely—but it has to be done under the guidance of the woman’s medical team, which can include her obstetrician, as well as physical therapists and dietitians, who collaborate on safe weight loss or maintenance efforts. 

Studies have shown that the following interventions can aid in safely losing weight while pregnant (Farpour-Lambert, 2018). 

• Exercise—Aerobic and resistance exercises should be done three to five times a week for 30 to 60 minutes each session. It is essential to choose a physical activity that is safe during pregnancy and avoid exercise with a high risk of falls or injury. 

• Diet modifications—The focus of diet modifications is to either decrease or maintain recommended calorie intake. Choosing foods such as whole grains, fruits, vegetables, and healthy proteins should be encouraged over high-calorie, less nutritious foods. Keeping a food diary is often recommended, as this can be a helpful tool for weight loss that can be reviewed with the dietitian. 

The efforts to lose or even maintain weight during pregnancy can be helpful to continue into the postpartum period. Healthy eating and exercise during pregnancy can lead to permanent lifestyle changes that improve overall wellness. 

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How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

August 16, 2022

Written by

Julie Scott

Fact checked by

Chimene Richa, MD

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About the medical reviewer

Chimene Richa, MD

Dr. Richa is a board-certified Ophthalmologist and medical writer for Ro.