Purpose: Energy metabolism is at the core of maintaining healthy body weights. Likewise, the assessment of energy needs is essential for providing adequate dietary advice. We explored differences in energy metabolism of a primigravid woman (age: 30 years) at 1 month prepregnancy ("baseline"), during pregnancy (33 weeks), and at 3 and 9 months postpartum. Measured versus estimated energy expenditure were compared using equations commonly used in clinical practice.
Methods: Energy metabolism was measured using a state-of-the-art whole body calorimetry unit (WBCU). Body composition (dual-energy X-ray absorptiometry), energy intake (3-day food records), physical activity (Baecke questionnaire), and breastmilk volume/breastfeeding energy expenditure (24-hours of infant test-retest weighing) were assessed.
Results: This case report is the first to assess energy expenditure in 3 different stages of a woman's life (prepregnancy, pregnancy, and postpartum) using WBCU. We noticed that weight and energy needs returned to prepregnancy values at 9 months postpartum, although a pattern of altered body composition emerged (higher fat/lean ratio) without changes in physical activity and energy intake. For this woman, current recommendations for energy overestimated actual needs by 350 kcal/day (9 months postpartum).
Conclusion: It is likely that more accurate approaches are needed to estimate energy needs during and postpregnancy, with targeted interventions to optimize body composition.