Differences in resting metabolic rate and physical activity patterns in lean and overweight/obese pregnant women

Abstract

Energy requirements vary during pregnancy due to changes in physical activity (PA) and maternal fat stores. This study measured resting metabolic rate (RMR) and PA patterns in healthy lean and overweight/obese (OW) pregnant women. RMR was measured using indirect calorimetry (MOXUS), activity patterns were estimated by omnidirectional accelerometers (Actical®) and body composition was measured using air displacement plethysmography (BodPod®). Nineteen pregnant women including 12 lean (BMI 18.5–24.9 kg/m2) and 7 OW (BMI 25–35 kg/m2) were assessed at 6–10, 12 and 24 weeks (wk) of gestation. Absolute RMR differed significantly between lean and OW women (1438 ± 49 vs. 1753 ± 62 kcal/day, p<0.05) at 6–10 wk. Moreover, when adjusted for weight, RMR (kcal/kg/d) differed (p<0.05) throughout pregnancy for lean and OW women (23 ± 1 vs. 21 ± 1, 24 ± 1 vs. 20 ± 1, 22 ± 1 vs. 19 ± 1 at 6–10, 12 or 24 wk, respectively). RMR was also positively correlated with fat mass and fat free mass in both groups (r=0.77, and r= 0.52, respectively, p<0.05). Although not significant, lean women spent ~50 more minutes in moderate to vigorous and ~150 less minutes in sedentary time compared to the OW over the 24 wk. In conclusion, OW women had lower RMR (kcal/kg/d) and decreased PA compared to lean women, suggesting a greater risk of excessive gestational weight gain and post partum weight retention. USDA‐ARS CRIS# 6251‐51000‐005‐03S.Grant Funding Source : USDA‐ARS CRIS# 6251‐51000‐005‐03S