The influence of energy metabolism on postpartum weight retention

Abstract

Background: Profiling postpartum energy metabolism may assist in optimizing weight management following childbirth.

Objectives: The aims of this study were to profile total energy expenditure (TEE), resting energy expenditure (REE), exercise energy expenditure, sleep energy expenditure, and respiratory quotient in women at 3 and 9 mo postpartum (3M-PP, 9M-PP, respectively), and to examine the association between energy metabolism and postpartum weight retention (PPWR).

Methods: In this cohort study, 1-h REE (measured in a whole body calorimetry unit, WBCU) and body composition (BC, measured by dual-energy X-ray absorptiometry) were measured at 3M-PP and 9M-PP (n = 49). Cardiorespiratory fitness [measured by the predicted maximal volume of oxygen consumption (p$\dot{V}$O2 max), n = 47] and 24-h TEE (WBCU, n = 43) were assessed only at 9M-PP. Women were stratified as high (>4.8 kg) or low (≤ 4.8 kg) weight retainers. Two-way mixed repeated-measures ANOVA and longitudinal regression models were applied. Linear regression was used to generate an equation at 3M-PP from the BC data, to predict the REE at 9M-PP.

Results: The fat mass at 3M-PP was positively associated with PPWR at 3M-PP (mean ± SE β: 0.09 ± 0.03; P = 0.005) and 9M-PP (β: 0.11 ± 0.04; P = 0.008), and negatively associated with REE at 3M-PP (β: -0.16 ± 0.02; P < 0.001) and TEE at 9M-PP (β: -0.15 ± 0.03; P < 0.001). REE was negatively associated with PPWR (β: -0.74; 95% CI: -1.29, -0.19; P = 0.0087). REE was 2 kcal/kg higher in low- vs. high-retainers at 3M-PP, and REE and TEE were both 4 kcal/kg higher in low- vs. high-retainers at 9M-PP. Low-retainers demonstrated an increase in REE greater than expected for changes in BC. PPWR was negatively associated with TEE (β: -0.08 ± 0.02; P = 0.0009) and p$\dot{V}$O2 max (β: -0.02 ± 0.01; P = 0.047); p$\dot{V}$O2 max was 7 mL · kg-1 · min-1 higher in low- vs. high-retainers (P = 0.047).

Conclusions: Energy metabolism, BC, and cardiorespiratory fitness may be associated with weight regulation and its trajectory during the postpartum period. This provides the foundation for future strategies to promote appropriate postpartum weight management.

Keywords: body composition; breastfeeding; cardiorespiratory fitness; energy expenditure; fat mass; gestational weight gain; postpartum weight retention; postpartum women; whole body calorimetry.