Do You Burn More Calories When Pregnant?

When pregnant, your weight can fluctuate widely. You could lose weight due to morning sickness, and you'll obviously gain weight as your pregnancy goes on and your baby grows. But there are many facets to weight gain, calories and what's healthy during pregnancy.  We spoke with Dr. Michael Rosenbaum to answer the question, 'Do you burn more calories while pregnant?'

Do you burn more calories when pregnant?

Yes, pregnant women do burn more calories while pregnant, says Dr. Michael Rosenbaum, a professor of pediatrics and medicine at Columbia University Medical Center. "Both your resting and total energy expenditure, or calories burned, increase, especially in the second and third trimesters," he says. He also notes that there is tremendous variability between individuals during pregnancy. "How much weight someone gains during pregnancy depends on how many calories they ingest relative to how many they burn and how much of the weight gained is water," he says.

It's not just the mom burning calories, either. Dr. Rosenbaum says that when considering energy expenditure or calories burned, it should refer to the number of calories burned by the mother and baby together, aka the maternal-fetal unit. "This is important because the fetus burns calories about four times faster, and this will become a bigger factor in determining energy expenditure as the fetus grows," he says.

Does your metabolism speed up during pregnancy?

Your metabolism does speed up, especially in those second and third trimesters, but it's due to your resting energy expenditure rather than activities like walking or exercising, according to Dr. Rosenbaum. "This is mostly, but not entirely, due to weight gain and is affected by the mother's degree of adiposity [body] before pregnancy," he explains.

For women who were not previously obese, the energy expenditure or calories gained increases by about 11o calories a day. For women who were obese before pregnancy, he says it's closer to 45 calories a day, again stressing how it can vary widely between individuals.

How much more energy do you burn when pregnant?

To put some numbers to it, Dr. Rosenbaum references a study done in 2021 that looked at how many average calories pregnant women burned per trimester. In the first trimester, the 24-hour energy expenditure or calories burned was about 144 calories daily. In the second, it jumped to 170, and by the third, it was around 290 calories per day. The resting energy expenditure accounted for many of the calories burned over the 24 hours.

FAQs

What types of foods are better for energy expenditure while pregnant?

Dr. Rosenbaum says that the recommendation for foods or food groups is the same whether you are pregnant or not. The Institute of Medicine recommends about 45% to 65% of your diet come from carbs, 10% to 35% from protein and 20% to 35% from good fats, with a limit on saturated and trans fats to help support your body and your growing baby. "There are no indications that the macronutrient composition, or what food groups you eat, in and of itself affects energy expenditure during pregnancy," he says.

Do you burn fat while pregnant?

Yes, you burn fat while you're pregnant, but you also burn carbs and a little bit of protein, depending on your diet and certain medical conditions that could affect what you absorb or burn. You should not try to lose weight while pregnant unless you are under the close supervision of a medical expert who has evaluated you for a condition such as gestational diabetes, high blood pressure or being at risk for preeclampsia.

What is considered a healthy weight gain while pregnant?

It depends on the body fat of the mother, says Dr. Rosenbaum. "The greater the adiposity [or] of the mother, the less weight they should gain during pregnancy, so long as they are gaining enough weight to 'feed the baby,'" he says. Going off of Body Mass Index (BMI), the below is recommended by the Institute of Medicine:

However, Dr. Rosenbaum notes that BMI does not consider how much of you is fat versus muscle, where your fat is or your health. A healthy pregnancy looks different for every body type. You should be monitored closely by your doctor throughout your pregnancy, who can alert you to any weight loss or gain that seems concerning.

Experts

• Dr. Michael Rosenbaum, professor of pediatrics and medicine at Columbia University Medical Center