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.