Can I Lose Weight While Pregnant?

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Most of us think of pregnancy as a time when we are “eating for two” and when we will be encouraged to gain a healthy amount of weight. But some of us may be wondering whether it’s ever okay to actually lose weight during pregnancy.

Perhaps you were in the middle of an intentional weight loss journey when you found out you were pregnant. Maybe a health care provider alerted you that you were considered overweight prior to pregnancy and you're wondering if losing a little weight during pregnancy might be healthy for you or your baby. Or maybe you are unintentionally losing weight because of morning sickness or hyperemesis and are unsure how much of a problem this is.

Although fluctuations in weight during pregnancy can be normal, such as during times of morning sickness and food aversion, intentional weight loss during pregnancy is almost never recommended. The exception would be if you are extremely overweight and a healthcare team determines that your weight might endanger your pregnancy.

As Kim Langdon, MD, an OB/GYN based in Ohio, puts it, "[Weight loss during pregnancy] is generally not recommended unless the mother’s [or birthing parent's] weight is a hazard to the pregnancy that could increase the risk of a complication, such as being too heavy to safely undergo an emergency cesarean section.”

Losing Weight During Pregnancy

In general, doctors and registered dietitians do not recommend intentional weight loss during pregnancy. Rarely, extreme obesity may make pregnancy and/or labor and delivery dangerous, and weight loss may be recommended. Still, most healthcare providers prefer to err on the side of caution because of the effects losing weight may have on the developing fetus.

Aubrey Phelps, MS, RDN, CLC, a functional perinatal and pediatric nutritionist, points out that current guidelines from the American College of Obstetricians and Gynecologists (ACOG) don’t recommend weight loss during pregnancy, but do allow for some “practitioner discretion” in certain situations, such as if a person is extremely overweight. Even then, usually the recommendation would be to maintain one’s current weight rather than losing weight.

Weight loss in the first trimester as a result of morning sickness is usually not a problem, especially if you gain an appropriate amount of weight further along in your pregnancy, explains Amy Shapiro, MS, RD, CDN, founder and director of Real Nutrition. Shapiro recommends you talk to a healthcare provider if your weight loss extends beyond the first trimester.

Dr. Langon says that a person’s weight may endanger their pregnancy when they are over about 300 pounds. A healthcare provider may also use your BMI (Body Mass Index) as a guide.

It’s also important to understand that being overweight doesn’t always mean that you will have an unhealthy pregnancy. Maintaining a healthy diet and exercise routine can go a long way in keeping you and your baby healthy during pregnancy, without making weight loss the focus.

Every pregnancy is different. Be sure to consult with a healthcare provider about your circumstances if you have any questions about losing weight while pregnant.

Is It Safe for Baby?

The main reason weight loss during pregnancy is usually discouraged is because of the ways it can potentially endanger the baby. This is why major health organizations like ACOG discourage maternal weight loss during pregnancy.

As ACOG explains, losing too much weight could restrict baby's growth. It may also predispose a person to a pre-term delivery, which can also be hazardous to the baby’s health. Tragically, in some cases, not gaining enough weight during pregnancy may increase a baby's risk of death.

Why You Should Not Lose Weight While Pregnant

It is rare that losing weight during pregnancy will be beneficial. Usually, the dangers that weight loss poses to your baby outweigh the benefits of losing weight. However, it is also important to understand the effects that being overweight may have on pregnancy.

As ACOG points out, being overweight increases the risk of giving birth to a baby with birth defects (including heart and neural tube defects) and giving birth prematurely. It can make diagnostic tests that are performed in pregnancy, such as ultrasounds and fetal heart rate monitoring, more difficult. It can increase the risk of having a “larger than normal” baby, which can make childbirth more difficult and increase the chances of having a C-section birth. Finally, being overweight can increase the risk of stillbirth.

If you are overweight and considering becoming pregnant, ACOG suggests that the best time to lose weight would be before you become pregnant. But if that doesn’t happen, there are many things you can do to stay healthy during your pregnancy and ensure the health and safety of your child. Maintaining a healthy, nutrient-dense diet and incorporating exercise into your routine are both immensely helpful, whatever your size and weight.

Risks of Losing Weight While Pregnant

Again, the greatest risk of losing weight during pregnancy, or not gaining adequate weight, is the ways it may endanger the baby. Let's take a more in-depth look at those dangers.

Slowed Growth in Babies

As Phelps explains, studies that looked at the pros and cons of weight loss during pregnancy found an “increased risk of small-for-gestational-age babies, which is a key risk factor for neonatal morbidity and mortality.”

There are many unknowns, says Phelps, and more research needs to be done in this area, but the fact that weight loss is known to affect a baby’s growth is why most providers will rarely recommend that pregnant people actively lose weight.

Premature Birth

Mothers who lose weight or do not gain enough weight may at be risk of premature delivery. "I've worked with a number of mothers due to babies measuring small and concerns about a need to deliver early to prevent the baby from continuing to grow in a sub-optimal environment," says Phelps.

ACOG explains that restrictive diets, even ones for pregnant parents who are unhealthily overweight, may increase the chances of preterm birth. Babies who are born preterm are at higher risk of immature lung development at birth and often need NICU care. Some premature babies go on to develop long-term disabilities.

Perinatal Mortality

ACOG explains that not gaining a healthy amount of weight or following a restrictive diet increases your risk of perinatal mortality (infant death). There are no exact statistics on this, but ACOG does note the link.

When Can I Resume Losing Weight?

You should talk to a healthcare provider about when exactly it will become safe for you to lose weight after you give birth. Generally speaking, it is safe to begin losing weight within a few weeks of giving birth.

You will naturally begin to lose weight in the days and weeks following birth, though much of that will be fluid loss, says Shapiro. After that, your weight will naturally shift to fat loss. Postpartum weight loss should happen gradually and the focus should be on nourishing foods, says Phelps. Don’t forget that you are recovering from pregnancy and labor, and postpartum is a time to recover.

If you are breastfeeding, you should keep in mind that breastfeeding requires extra calories and that if you lose weight too quickly, you will likely begin to feel depleted. According to the CDC, breastfeeding requires an additional 450-500 calories, so you should factor that in as you consider losing weight while breastfeeding. Again, rather than restricting calories, focusing on eating whole foods and finding ways to incorporate healthy movement into your day should be the focus.

Pregnancy Safe Alternatives

While losing weight is almost never a goal you should be focused on during pregnancy, that doesn’t mean you shouldn’t work on staying healthy and making healthy lifestyle choices. Depending on your weight and overall health, a healthcare provider may encourage you to gain less weight than people who enter pregnancy at a healthy weight. In some cases, a provider may recommend that you gain very little weight, but instead maintain your current weight.

Focus On A Nutrient-Rich Diet

While most people will need to increase their calories during pregnancy, if your gain is to either maintain your weight or not gain too much weight, you can focus on eating whole, nutrient-dense foods.

Simply giving up processed foods and fast foods and focusing on whole foods can help immensely. Natalie Kravat, MS, RDN, a registered dietitian, recommends eating a diet that is focused on protein and veggies. This will not only help you maintain or gain a healthy weight during pregnancy, but make weight loss after pregnancy easier.

“Focus on filling half your plate with non-starchy vegetables, a quarter of the plate with protein, and a quarter with nutrient-dense starches (sweet potato, quinoa, etc.),” Kravat suggests.

Incorporate Movement Into Your Day

ACOG states that as long as you are experiencing an otherwise healthy pregnancy, exercising during pregnancy is safe. “Maintaining a consistent exercise program will help the woman to recover faster after delivery and to lose weight quickly after pregnancy,” says Kravat.

If you have never exercised before, you will want to take it slow, but for most birthing parents, incorporating moderate-intensity exercises is fine. ACOG contends that the safest exercises for pregnant people include walking, swimming, gardening, and stationary biking, along with yoga and Pilates (both modified for pregnancy).

Consult With a Registered Dietitian

If it’s determined that losing weight (or maintaining your weight and not gaining) is important for the health of your pregnancy and for a healthy delivery, you will need to work closely with a healthcare provider to ensure that you are getting the nutrition and calories you need, both for yourself and your growing baby.

Again, since healthcare providers rarely recommend weight loss, when they do, they will be working carefully with you to ensure that the weight loss (or weight maintenance) is done in a safe manner.

A Word From Verywell

It’s natural to feel concerned about your weight during pregnancy, whether it’s being preoccupied with not gaining too many unwanted pounds, or feeling unsure if you should lose weight to maintain a healthy pregnancy.

However, it is rarely advisable to actively lose weight during pregnancy, and you should never adopt a calorie-restrictive diet. In the rare circumstance that weight loss during pregnancy is a good idea, the decision to do so should only be made in collaboration with a healthcare provider.

If you have any questions or concerns about your weight during pregnancy, and how you can best maintain a healthy pregnancy for both you and your baby, talk to a doctor or midwife.

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Article Sources
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  1. American College of Obstetricians and Gynecologists. Weight Gain During Pregnancy. Updated December 31, 2020.

  2. American College of Obstetricians and Gynecologists. Weight Gain During Pregnancy. Updated December 31, 2020.

  3. American College of Obstetricians and Gynecologists. Weight Gain During Pregnancy. Updated December 31, 2020.

  4. American College of Obstetricians and Gynecologists. Weight Gain During Pregnancy. Updated December 31, 2020.

  5. Centers for Disease Control and Prevention. Maternal Diet. Updated October 8, 2020.

  6. American College of Obstetricians and Gynecologists. Exercise During Pregnancy. Updated July 1, 2019.

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