Calorie needs change by trimester, not all at once
"Eating for two" is a popular phrase, but it overstates how much extra energy pregnancy actually requires — and the increase isn't constant throughout pregnancy. Energy needs rise gradually as the pregnancy progresses, reflecting accelerating fetal growth in later trimesters.
1st trimester: +0 kcal/day
2nd trimester: +340 kcal/day
3rd trimester: +450 kcal/day
These additions are on top of pre-pregnancy TDEE (Total Daily Energy Expenditure) — not a fixed number for everyone, since baseline energy needs already vary by height, weight, age, and activity level.
Quality matters alongside quantity
The additional calories during pregnancy are most valuable when they come from nutrient-dense foods — the body's needs for protein, iron, folate, calcium, and other nutrients increase more proportionally than total calorie needs do, making nutrient density an important consideration alongside the calorie number itself.