Can You Lose Weight In The First Trimester? Here’s What To Know

Unless you’re in early pregnancy, it’s generally not considered safe to lose weight while pregnant. If you’re actively trying to lose weight or dieting, you might not be getting all the important nutrients you and your developing baby need for a healthy pregnancy.

Headshot of Dr. Cheryl Axelrod, medical reviewer for pregnancy weight information

Medically reviewed by Cheryl Axelrod, M.D., ob-gyn

Professional photo of Karen Miles, author of this article on pregnancy

Written by Karen Miles

Pregnant woman looking at her phone, symbolizing researching pregnancy topics like weight lossPhoto credit: Sarah Ottavis for BabyCenter

Is it safe to lose weight while pregnant?

Generally speaking, no, it’s not safe to intentionally lose weight while pregnant, regardless of your starting weight. (A key exception here is during the early weeks of pregnancy – more on this below).

The relationship between a mother’s weight during pregnancy and its impact on her baby is complex and an ongoing area of study. However, experts agree that deliberate weight loss throughout most of pregnancy isn’t compatible with supporting a healthy baby’s growth. Furthermore, if you are losing weight due to dieting or insufficient intake, you may not be consuming enough calories and essential nutrients required for a healthy pregnancy.

While being overweight or obese before or during pregnancy increases the risk of certain complications, trying to lose weight during pregnancy can put you at risk of delivering a baby who is too small (classified as small for gestational age, or SGA) and may also increase the likelihood of preterm birth.

can you lose weight while pregnant first trimester

What if I lose weight in the first trimester?

It can actually be normal to lose weight in the first trimester of pregnancy. Several factors can contribute to this early weight loss:

• Morning sickness: Nausea and vomiting are very common in the first trimester due to morning sickness. This can significantly reduce your appetite, and vomiting means losing consumed calories. In most cases, your baby will still receive the necessary calories and nutrients during this early stage, even if you lose a few pounds.
• Existing fat reserves: If you were overweight or obese before becoming pregnant, you have extra stored fat that provides a calorie reserve. As your baby begins to grow, it’s often not harmful to maintain your weight or even lose a small amount initially, as your body can draw on these reserves.
• Improved lifestyle: You might experience early weight loss if you adopt healthier habits upon finding out you’re pregnant, such as starting a regular exercise routine or switching to more nutritious foods.

In most situations, this initial weight loss isn’t dangerous. However, you should inform your healthcare provider immediately if you are losing a significant amount of weight, or if you suspect you might have hyperemesis gravidarum (a severe form of morning sickness characterized by extreme nausea and vomiting).

can you lose weight first trimester

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

If you started your pregnancy carrying excess weight for your height, you’re not alone – over half of pregnant women fall into the overweight or obese category.

You are considered overweight if your pre-pregnancy body mass index (BMI) is between 25.0 and 29.9. BMI estimates body fat based on your height and weight. You are classified as obese if your pre-pregnancy BMI is 30.0 or higher.

If you’re unsure about your BMI, there are many online calculators available.

Pregnancy weight gain recommendations vary based on your pre-pregnancy BMI:

• If your BMI is 25.0 to 29.9: The recommended total weight gain is typically between 15 and 25 pounds by the end of your pregnancy. This usually averages out to gaining about 2 to 3 pounds per month during your second and third trimesters.
• If your BMI is 30.0 or higher: The general recommendation is to gain 11 to 20 pounds throughout the entire pregnancy.

Your healthcare provider can give you personalized guidance on your target weight gain. While losing weight during pregnancy isn’t advised, if you are overweight or obese, it might be safe (and potentially beneficial) for you to gain less than the standard recommended amount, but only under the close supervision and guidance of your healthcare provider.

The Institutes of Medicine (IOM) provides these pregnancy weight gain recommendations, and there has been some discussion and controversy regarding the specific amounts suggested for obese women. One point of contention is that the IOM provides a single recommendation for all women with a BMI of 30 or higher, without differentiating between different classes of obesity.

can you lose weight in the first trimester

Some research suggests that for overweight or obese women, gaining less than the IOM guidelines might be safe and associated with similar or even better outcomes for the newborn compared to women who gain the full recommended 15 to 20 pounds. For example, some studies found that overweight or obese women who gained only 6 to 14 pounds had positive neonatal outcomes.

It is crucial to discuss your specific target weight gain during pregnancy with your healthcare provider if you are overweight or obese. If you plan to gain less than the standard recommendations, they will need to monitor your progress and your baby’s growth closely to ensure everything is proceeding healthily.

Can I diet to lose weight during pregnancy?

Pregnancy is absolutely not the appropriate time to go on a weight-loss diet, regardless of your starting weight. Restricting your food intake can be potentially dangerous for both you and your developing baby. You need sufficient calories and nutrients to support a healthy pregnancy and ensure your baby develops properly.

Additionally, you should avoid restrictive diets, especially those that severely limit carbohydrates, such as keto or Atkins diets. Your growing baby requires carbohydrates for energy and development, and sustained ketosis caused by these types of diets can potentially harm a developing fetus.

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Instead of dieting, focus on managing your weight gain within your target range by concentrating on eating healthfully and engaging in regular, appropriate exercise. Aim to:

• Eat balanced meals and healthy snacks throughout the day.
• Stay well-hydrated by drinking plenty of water – typically around ten 8-ounce cups daily.
• Choose complex carbohydrates, such as fruits, vegetables, beans, and whole grains, over simple carbohydrates like white bread, white rice, and sugary foods.
• Monitor your weight regularly with your healthcare provider to stay on track with your goals.

can you lose weight your first trimester

Weight loss during pregnancy: Warning signs

Losing weight in the second or third trimester could be a sign of an underlying issue. While sometimes harmless (like temporary water loss after fluid retention), it’s essential to inform your healthcare provider if you experience weight loss during these later stages.

Your provider will likely assess your eating habits and activity levels and ask about any other symptoms you might have, such as nausea, heartburn, bloating, or constipation. These issues can understandably make it difficult for expectant mothers to eat enough. Your provider might also recommend screening for conditions like depression or potential fetal growth restriction, which can sometimes be associated with insufficient weight gain or loss.

It is particularly important to contact your provider immediately if you experience sudden or dramatic weight loss, such as losing five pounds or more in a single week.

Conclusion

While intentional weight loss is not recommended during pregnancy, especially after the first trimester, losing a few pounds in early pregnancy can be a normal occurrence due to factors like morning sickness or starting pregnancy overweight. Attempting to diet while pregnant is unsafe and can deprive your baby of necessary nutrients. Focus instead on healthy eating and appropriate exercise. If you have concerns about your weight, are losing a significant amount, or experience weight loss in the later trimesters, always consult your healthcare provider. They can provide personalized guidance and ensure your pregnancy is progressing healthily.