Can You Lose Weight in the First Trimester? Understanding the Facts

Losing weight during pregnancy is generally not recommended, regardless of your starting weight, as it can potentially deprive you and your developing baby of essential nutrients. However, many wonder, Can You Lose Weight In The First Trimester specifically? While intentional weight loss is unsafe, some weight fluctuation early on can occur and may not be cause for alarm. Understanding the reasons behind this and the overall guidelines for pregnancy weight is crucial.

Why Weight Loss Might Occur in Early Pregnancy

It’s not uncommon for some individuals to experience a slight weight decrease during the initial weeks of pregnancy. This early pregnancy weight loss is often temporary and can be attributed to several factors:

• Morning Sickness: A frequent companion in the first trimester, morning sickness involves nausea and sometimes vomiting. This can naturally lead to a reduced appetite and lower calorie intake, potentially causing temporary weight loss. Rest assured, at this early stage, your baby typically still receives the necessary nutrients.
• Utilizing Fat Reserves: Women who start pregnancy overweight or obese have additional calorie reserves stored as body fat. As the baby begins to grow, the body might tap into these reserves, which can result in maintaining or slightly losing weight initially without harm.
• Improved Lifestyle Choices: Upon discovering they are pregnant, many individuals adopt healthier habits. Starting a moderate exercise routine (with provider approval) or switching to more nutritious foods can sometimes lead to a small amount of weight loss early on.

While these scenarios are often normal, significant or persistent weight loss should always be discussed with your healthcare provider. If you suspect severe morning sickness, known as hyperemesis gravidarum, seek medical attention promptly.

Pregnant woman sitting outdoors checking phone for information on first trimester weight loss concerns.

Is Intentional Weight Loss During Pregnancy Safe?

Outside of the specific circumstances mentioned for early pregnancy, actively trying to lose weight while pregnant is not considered safe. Losing weight, especially through dieting, can mean missing out on vital calories and nutrients essential for your baby’s healthy development. This practice is linked to potential risks, including having a baby that is small for gestational age (SGA) or experiencing preterm birth. Even if you are overweight or obese, pregnancy is not the time for weight loss efforts.

How Much Weight Should You Gain if Overweight or Obese?

Managing weight gain appropriately is important, especially if you begin your pregnancy with a higher Body Mass Index (BMI). BMI is an estimate of body fat based on height and weight.

• Overweight: Pre-pregnancy BMI between 25 and 29.9.
• Obese: Pre-pregnancy BMI of 30 or greater.

The Institute of Medicine (IOM) provides general guidelines for pregnancy weight gain based on pre-pregnancy BMI:

• BMI 25 to 29.9: Recommended gain is 15 to 25 pounds total, averaging about 2 to 3 pounds per month in the second and third trimesters.
• BMI 30 or higher: Recommended gain is 11 to 20 pounds total.

While intentionally losing weight is unsafe, some research suggests that women who are overweight or obese might safely gain less than the standard IOM guidelines, provided they receive close monitoring from their healthcare provider. Studies have indicated that gaining only 6 to 14 pounds resulted in comparable or sometimes better outcomes for babies compared to gaining the recommended 15 to 20 pounds in some overweight/obese groups. Always discuss your personal weight gain target with your provider, who will monitor both your health and your baby’s growth throughout the pregnancy.

Can I Diet During Pregnancy?

No, pregnancy is absolutely not the time to start a weight-loss diet. Restricting food intake can be hazardous. Your body requires sufficient calories and a wide range of nutrients to support both your health and your baby’s growth.

Avoid restrictive diets, particularly those low in carbohydrates like the keto or Atkins diets. Carbohydrates are crucial for your baby’s development, and the ketosis induced by such diets can be harmful to a growing fetus.

Focus instead on managing your weight gain within the recommended range through healthy habits:

• Eat balanced meals and choose nutritious snacks.
• Stay well-hydrated, aiming for about ten 8-ounce glasses of water daily.
• Prioritize complex carbohydrates (whole grains, beans, fruits, vegetables) over simple ones (white bread, white rice, sugary foods).
• Regularly monitor your weight gain progress with your healthcare provider.

Weight Loss During Pregnancy: When to Be Concerned

While some weight loss in the first trimester can be normal due to factors like morning sickness, losing weight in the second or third trimester generally warrants attention. Though sometimes it might be due to temporary water weight fluctuations, it could also indicate an underlying issue.

Inform your provider about any weight loss during these later stages. They will evaluate your diet, activity levels, and inquire about symptoms like persistent nausea, heartburn, bloating, or constipation, which can affect appetite. They may also screen for conditions like depression or assess fetal growth. A sudden, dramatic weight loss, such as losing five pounds in a single week, requires immediate medical attention.

Conclusion

Experiencing some weight loss in the first trimester can be normal, often linked to morning sickness or positive lifestyle changes. However, intentional weight loss or dieting during any stage of pregnancy is unsafe and not recommended due to the risk of nutrient deficiencies and potential harm to the baby. Focus on steady, appropriate weight gain guided by your healthcare provider, achieved through a balanced diet and healthy habits. Always communicate any concerns about weight changes, especially significant or later-term weight loss, to your doctor or midwife for proper assessment and guidance.

References

ACOG. 2021. Nutrition during pregnancy. American College of Obstetricians and Gynecologists. https://www.acog.org/womens-health/faqs/nutrition-during-pregnancy

ACOG. 2021. Obesity and pregnancy. American College of Obstetricians and Gynecologists. https://www.acog.org/womens-health/faqs/obesity-and-pregnancy

ACOG. 2020. Weight gain during pregnancy. American College of Obstetricians and Gynecologists. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2013/01/weight-gain-during-pregnancy

IOM. 2009. Weight gain during pregnancy: Reexamining the guidelines. The National Academies Press, Washington D.C. https://www.ncbi.nlm.nih.gov/books/NBK32813/

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 https://pubmed.ncbi.nlm.nih.gov/26196130/

March of Dimes. 2020. Being overweight during pregnancy. https://www.marchofdimes.org/pregnancy/being-overweight-during-pregnancy.aspx

Rasmussen KM et al. 2010. Recommendations for weight gain during pregnancy in the context of the obesity epidemic. Obstetrics & Gynecology 116(5): 1191-1195. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4288953/

Robillard PY et al 2018. Relationship between pre-pregnancy maternal BMI and optimal weight gain in singleton pregnancies. Heliyon 4(5) E00615. https://www.cell.com/heliyon/fulltext/S2405-8440(18)30300-1

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. https://pubmed.ncbi.nlm.nih.gov/19788965/