Changes in resting and walking energy expenditure and walking speed during pregnancy in obese women

Abstract

Background: Energy-conserving processes reported in undernourished women during pregnancy are a recognized strategy for providing the energy required to support fetal development. Women who are obese before conceiving arguably have sufficient fat stores to support the energy demands of pregnancy without the need to provoke energy-conserving mechanisms. Objective: We tested the hypothesis that obese women would show behavioral adaptation [ie, a decrease in self-selected walking (SSW) speed] but not metabolic compensation [ie, a decrease in resting metabolic rate (RMR) or the metabolic cost of walking] during gestation. Design: RMR, SSW speed, metabolic cost of walking, and anthropometric variables were measured in 23 women aged 31 6 4 y with a BMI (in kg/m 2 ) of 33.6 6 2.5 (mean 6 SD) at ;15 and 30 wk of gestation. RMR was also measured in 2 cohorts of nonpregnant control subjects matched for the age, weight, and height of the pregnant cohort at 15 (n = 23) and 30 (n = 23) wk. Results: Gestational weight gain varied widely (11.3 6 5.4 kg), and 52% of the women gained more weight than is recommended. RMR increased significantly by an average of 177 6 176 kcal/d (11 6 12%; P , 0.0001); however, the within-group variability was large. Both the metabolic cost of walking and SSW speed decreased significantly (P , 0.01). Whereas RMR increased in .80% of the cohort, the net oxygen cost of walking decreased in the same proportion of women. Conclusion: Although the increase in RMR was greater than that explained by weight gain, evidence of both behavioral and biological compensation in the metabolic cost of walking was observed in obese women during gestation. The trial is registered with the Australian Clinical Trials Registry as ACTRN012606000271505.Am J Clin Nutr 2011;94:819-30.

Resting Energy Expenditure Relationship with Macronutrients and Gestational Weight Gain: A Pilot Study

“…In our study, there was an overall increase in REE throughout the study of 11.5%. This is similar to other studies that have assessed REE that found increases ranging from 13% to 35% [8,11,[15][16][17]. The large range in changes in REE throughout pregnancy is reflective of the population being studied, the body weight status prior to the study, and the duration of data collection (e.g., preconception to postpartum).…”

“…Real-time, mobile tracking of REE has become increasingly popular but few devices are able to accurately estimate caloric needs [12]; further, they have rarely been used in pregnant populations [13,14]. Changes in REE during pregnancy have demonstrated an overall increase in caloric needs [8,11,[15][16][17] ranging from 13-35%. Recently, the Breezing™ device, a hand-held, Bluetooth-enabled metabolism tracker, that uses indirect calorimetry to measure REE was developed and validated against the laboratory-based Douglas Bag Method [18].…”

Does metabolic compensation explain the majority of less-than-expected weight loss in obese adults during a short-term severe diet and exercise intervention?

“…We have recently shown in obese pregnant women that, over gestation, the energy cost of movement can decrease, and that this is because of both behavioural (walking more slowly) and biological (improved walking economy) compensations. 38 Further, we, and others, have shown reductions in non-exercise activity thermogenesis in overweight and obese individuals in response to exercise training and/or caloric restriction interventions. [39][40][41] Given that accurate measurement of daily physical activity and activity energy expenditure can be challenging in studies of freeliving humans, it is useful to consider evidence from highlycontrolled animal studies.…”

Lack of a significant relationship between energy intake in pregnancy and gestational weight gain underlines the need for further evaluations of energy metabolism during this time

“…Importantly, the dynamic changes that occur in biological and behavioural adaptations to pregnancy are complex and difficult to capture using simple measures at a few time points. Others have documented increases in resting energy expenditure accompanied by even larger decreases in physical activity-related energy expenditure in pregnancy,5 6 although dietary intake measurements were not made in these studies.…”