The Institute of Medicine and the American College of Obstetricians and Gynecologists recommend that women maintain pregravid calorie consumption during the first trimester for the recommended weight gain of 0.5 to 2 kg in the first trimester since weight gain's energy expenditures are deemed low. Pregnant women should eat an extra 100 to 200 kcals per day, provided their physical activity does not decrease, according to the energy intake requirement model.