During which period does a woman’s energy requirement increase significantly?

The correct answer is lactation. During lactation, a woman's energy requirements increase significantly to support milk production for breastfeeding. This heightened demand is necessary because milk contains proteins, fats, vitamins, and minerals that are essential for the infant's growth and development. A lactating woman typically requires an additional 450 to 500 calories per day to maintain her own health while producing enough milk for her baby.

Pregnancy also increases energy needs, as the body must support the growth and development of the fetus. However, the energy requirement peaks during lactation when the mother is actively producing and supplying milk.

Before pregnancy, energy needs are generally stable and aligned with usual requirements for a woman's metabolic demands, while energy needs during adolescence can vary widely but do not specifically correlate with a significant sustained increase like that observed in lactation. Hence, lactation is the critical period marked by the most substantial energy requirement increase.