Increased Energy Intake After Pregnancy Determines Postpartum Weight Retention in Women With Obesity

Abstract

Context: This study was designed to understand causes and critical periods for postpartum weight retention by characterizing changes in body composition, energy intake, energy expenditure and physical activity in women with obesity during pregnancy and postpartum.

Design: In this prospective, observational cohort study, body composition (plethysmography), energy expenditure (doubly labeled water, whole-body room calorimetry), physical activity (accelerometry), metabolic biomarkers, and eating behaviors were measured. Energy intake was calculated by the intake-balance method for pregnancy, and for 2 postpartum periods (0 to 6 months and 6 to 12 months).

Results: During the 18-month observation period, weight loss occurred in 16 (43%) women (mean ± SEM, -4.9 ± 1.6 kg) and weight retention occurred in 21 (57%) women (+8.6 ± 1.4 kg). Comparing women with postpartum weight loss and weight retention, changes in body weight were not different during pregnancy (6.9 ± 1.0 vs 9.5 ± 0.9 kg, P = 0.06). After pregnancy, women with postpartum weight loss lost -3.6 ± 1.8 kg fat mass whereas women with weight retention gained 6.2 ± 1.7 kg fat mass (P < 0.001). Women with postpartum weight loss reduced energy intake during the postpartum period (compared with during pregnancy) by 300 kcal/d (1255 kJ/d), while women with weight retention increased energy intake by 250 kcal/d (1046 kJ/d, P < 0.005). There were no differences in the duration of breastfeeding, eating behavior, or metabolic biomarkers.

Conclusions: Postpartum weight gain was the result of increased energy intake after pregnancy rather than decreased energy expenditure. Dietary intake recommendations are needed for women with obesity during the postpartum period, and women should be educated on the risk of overeating after pregnancy.

Trial registration: ClinicalTrials.gov NCT01954342.

Keywords: diet quality; energy intake; food photography; metabolic rate; physical activity; postpartum weight loss.

© Endocrine Society 2020. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Figures

Figure 1.

Changes in body weight and composition during and after pregnancy in women with obesity and postpartum weight retention (PPWR) or weight loss (PPWL). Data are presented per individual (Panel 1A, n = 37), as weekly mean (Panel 1B, n = 30), and as mean ± SEM (Panel 1C and 1D, n = 37). Panels 1E and 1F show individual data points for the association between changes in body weight and change in mass of body component (in kg: fat mass [FM]; fat-free mass [FFM]). Regression lines are shown for significant associations (Pregnancy; FM: R2 = 0.51, P < 0.001; FFM: R2 = 0.16, P = 0.02; Postpartum; FM: R2 = 0.88, P < 0.001). *Reflects a statistical significance (P < 0.05) of the time × group interaction, indicating that the change in weight between 2 consequent measures was different between the PPWL and PPWR groups.

Figure 2.

Energy intake during and after pregnancy in women with obesity and postpartum weight retention (PPWR) or postpartum weight loss (PPWL). Data are reported as individual data (triangles) and mean ± SEM (bars). Pregnancy refers to the period from early to late pregnancy. *Indicates statistical significance (P < 0.05) between the PPWL and PPWR groups.

Figure 3.

Energy expenditure and physical activity during and after pregnancy in women with obesity and postpartum weight retention (PPWR) or weight loss (PPWL). Data are reported as mean ± SEM. Panel A: Total daily EE was measured over 7 days using doubly labeled water; differences between groups after adjustment for body mass (fat-free mass and fat mass). TDEEadj[kcal/d] = 918 + 33.45 × FFM[kg] − 1.75 × FM[kg]; R2 = 0.29; P = 0.003. Panel B, SleepEEadj[kcal/d] = 296 + 22.34 × FFM[kg] +5.07 FM[kg]; R2 = 0.67; P < 0.001). Abbreviations: EE, energy expenditure; ENMO, Euclidian norm minus 1; FFM, fat-free mass; FM, fat mass; TDEE, total daily energy expenditure.