Can you lose weight while pregnant?

Unless you're in early pregnancy, it's not safe to lose weight while pregnant. If you're losing weight or dieting, you may miss out on important nutrients you need for a healthy pregnancy.

pregnant woman sitting on bench
Photo credit: Sarah Ottavis for BabyCenter

Can I lose weight while pregnant?

No matter how much you weigh, it's not safe to lose weight while pregnant. (The one exception to this in the early weeks of pregnancy – see the reasons why below.)

The effect of a mom's weight gain or loss on her baby during pregnancy is a complicated issue that experts continue to study, but we know that losing weight during pregnancy isn't compatible with growing a healthy baby. And if you're losing weight, you may not be getting all the calories and nutrients you need for a healthy pregnancy.

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While being overweight or obese during pregnancy increases your risk for some pregnancy complications, losing weight during pregnancy puts you at risk of having a baby who is too small (small for gestational age, or SGA) and for preterm birth.

What if I lose weight in early pregnancy?

It can be normal to lose weight in early pregnancy, due to:

  • Morning sickness. In the first trimester, it's common to lose weight as the result of morning sickness. The nausea can diminish your appetite, and the vomiting can cause you to miss out on calories. Don't worry, your baby will get all the necessary calories and nutrients they need at this point.
  • Fat reserves. Overweight women have an extra reserve of calories in stored fat, so as your baby grows, it's not harmful to maintain or even lose a little weight at first.
  • Improved lifestyle. You might lose weight early on if you've started exercising or eating healthier foods when you became pregnant.

In most cases, this weight loss isn't dangerous. If you're losing a lot of weight, though, or if you think you may be suffering from hyperemesis gravidarum (severe morning sickness), tell your provider right away.

How much weight to gain if you're pregnant and overweight or obese

If you started off your pregnancy carrying too much weight for your height, you're not alone. More than half of pregnant women are overweight or obese.

You're considered overweight if your pre-pregnancy body mass index (BMI) is between 25 and 29.9. (Your BMI reflects the relationship between your height and weight, and is an estimate of body fat.) You're considered obese if your BMI is 30 or greater.

Not sure what your BMI is? Try this BMI calculatorOpens a new window.

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How much to gain during pregnancy depends on your BMI:

  • If your BMI is 25 to 29.9: It's recommended that you gain between 15 and 25 pounds by the end of your pregnancy, or approximately 2 to 3 pounds per month in your second and third trimesters.
  • If your BMI is 30 or higher: You're advised to gain 11 to 20 pounds during pregnancy.

For guidance, try our pregnancy weight gain calculator and learn more about pregnancy weight gain.

Though it's not safe to lose weight during pregnancy, if you're overweight or obese during pregnancy you may be able to safely gain less than the recommended amount – with your healthcare provider's guidance and monitoring.

Pregnancy weight gain recommendations are provided by the Institutes of Medicine (IOM), and there's been some controversy about the IOM amounts stated for obese women. One issue is that the IOM provided one recommendation for all obese women (those with a BMI of 30 or higher) rather than different numbers for different categories of obesity.

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According to some researchers, if you're overweight or obese, it may be safe (and advantageous) for you to gain less than IOM guidelines recommend. Some studies show that overweight or obese women who gain only 6 to 14 pounds had similar or better neonatal outcomes than women who gained the recommended 15 to 20 pounds, for example.

If you're overweight or obese, talk with your provider about your target weight gain during pregnancy. If you gain less weight than recommended, they'll want to monitor you and your baby to be sure your pregnancy is progressing well and your baby is growing appropriately.

Can I diet to lose weight during pregnancy?

Pregnancy is definitely not the time to go on a weight-loss diet, no matter what weight you're at. Restricting your food intake is potentially hazardous to you and your developing baby. You need enough calories and nutrients to support a healthy pregnancy and baby.

Also, steer clear of carbohydrate-restrictive diets such as keto and Atkins. Your growing baby needs the carbohydrates, and ongoing ketosis caused by these diets can harm a developing fetus.

During pregnancy, you can keep your weight gain within your target range by eating healthfully and exercising regularly. Do your best to:

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  • Eat balanced meals and healthy snacks.
  • Stay hydrated by drinking an average of about ten 8-ounce cups of water each day.
  • Choose complex carbs – such as beans, fruits and vegetables, and whole grains – over simple carbohydrates such as white bread, white rice, and white pasta.
  • Monitor your weight with your healthcare provider to make sure you're on track.

For more tips, read our article on how to avoid gaining too much weight during pregnancy.

Weight loss during pregnancy: Warning signs

Losing weight in the second or third trimester can signal a problem. In some cases, weight loss can be harmless (a result of water loss after temporary retention, for example), but it's important to let your provider know.

They'll assess your diet and activity habits and ask questions about symptoms, such as nausea, heartburn, bloating, and constipation, all of which can understandably discourage expecting moms from eating. Your provider may also want to screen you for depression or fetal growth restriction.

Also, tell your provider immediately if you have suddenly have a dramatic weight loss, such as five pounds in a week.

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BabyCenter's editorial team is committed to providing the most helpful and trustworthy pregnancy and parenting information in the world. When creating and updating content, we rely on credible sources: respected health organizations, professional groups of doctors and other experts, and published studies in peer-reviewed journals. We believe you should always know the source of the information you're seeing. Learn more about our editorial and medical review policies.

ACOG. 2021. Nutrition during pregnancy. American College of Obstetricians and Gynecologists. a new window [Accessed August 2021]

ACOG. 2021. Obesity and pregnancy. American College of Obstetricians and Gynecologists. a new window [Accessed August 2021]

ACOG. 2020. Weight gain during pregnancy. American College of Obstetricians and Gynecologists. a new window [Accessed August 2020]

IOM. 2009. Weight gain during pregnancy: Reexamining the guidelines. The National Academies Press, Washington D.C. a new window [Accessed August 2021]

Kapadia MZ et al. 2015. Weight loss instead of weight gain within the guidelines in obese women during pregnancy: A systematic review and meta-analyses of maternal and infant outcomes. PLoS One 10(7): e0132650 a new window [Accessed August 2021]

March of Dimes. 2020. Being overweight during pregnancy. a new window [Accessed August 2021]

Rasmussen KM et al. 2010. Recommendations for weight gain during pregnancy in the context of the obesity epidemic. Obstetrics & Gynecology 116(5): 1191-1195. a new window [Accessed August 2020]

Robillard PY et al 2018. Relationship between pre-pregnancy maternal BMI and optimal weight gain in singleton pregnancies. Heliyon 4(5) E00615. a new window [Accessed August 2021]

Siega-Riz AM et al. 2009. A systematic review of outcomes of maternal weight gain according to the Institute of Medicine recommendations: birthweight, fetal growth, and postpartum weight retention. American Journal of Obstetrics and Gynecology 201:339. E1-14. a new window [Accessed August 2021]

Karen Miles
Karen Miles is a writer and an expert on pregnancy and parenting who has contributed to BabyCenter for more than 20 years. She's passionate about bringing up-to-date, useful information to parents so they can make good decisions for their families. Her favorite gig of all is being "Mama Karen" to four grown children and "Nana" to nine grandkids.