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Objective The aim of this study was to examine changes in body weight and fat in Black and White women during the first postpartum year and to determine whether there is preferential retention of fat mass and abdominal fat. Methods Body composition was quantified by dual‐energy x‐ray absorptiometry in Black (n = 49) and White (n = 85) women at 6 to 8 weeks, 6 months, and 12 months after delivery of a singleton infant. Results Weight, fat mass, percent body fat, and fat in the trunk, android, gynoid, and limb regions decreased from 6 to 8 weeks to 12 months in White women, but not in Black women (fat mass, adjusted mean [SE]: 29.6 [1.3] to 26.9 [1.3] kg in White women and 34.5 [1.5] to 36.8 [1.8] kg in Black women). In the entire sample, fat mass was higher at 6 months than at 6 to 8 weeks, independent of weight change; visceral fat was higher at 12 months (686 [45] g) than at 6 to 8 weeks (611 [42] g) and 6 months (626 [43] g); and android fat was higher at 12 months than at 6 months, independent of fat change. Conclusions Black women were less likely than White women to lose weight and fat in the postpartum period. There was preferential retention of fat in the abdominal area.

The ActiGraph GT3X+ (ActiGraph LLC, Pensacola, FL) has been worn on the wrist in studies with the purpose of measuring sleep. However, its performance in assessing physical activity (PA) when worn on the wrist remains unclear. PURPOSE: This study examined the performance of the wrist-worn GT3X+ accelerometer in measuring energy expenditure of PA (PAEE) and classifying PA intensity in a healthy, nonobese population of older women. METHODS: Women [n=89, age=65.6 (4.3)] wore the GT3X+ and the SenseWear Armband Mini monitor (SWAM, BodyMedia Inc. Pittsburgh, PA) concurrently for 2 weeks when then doubly labeled water method (DLW) was used to determine total daily energy expenditure (EE). Indirect calorimetry was performed on the last day of the 2 weeks to determine resting EE. Manufacturer-provided software was used to process GT3X+ (2 equations were selected) and SWAM data. Bivariate correlations, Intra Class Correlations, and Bland-Altman plots were performed to evaluate agreement between the GT3X+ and criterion measures for time spent in sedentary, light and moderate-to-vigorous PA (determined by SWAM) and PAEE (determined by SWAM and by DLW and resting EE). An epoch-by-epoch (EBE) analysis was performed to evaluate discrepancy and agreement of PA intensity classification between the GT3X+ and the SWAM. RESULTS: For PAEE, the GT3X+ showed a moderate correlation with criterion measures (r = 0.413 and 0.400 with the SWAM and r = 0.564 and 0.501 with DLW and resting EE), but Bland-Altman plots showed large variability. When estimating time spent in PA intensity, the GT3X+ underestimated sedentary time and overestimated PA intensity when compared to the SWAM. During the EBE analysis, the GT3X+ misclassified light intensity PA as moderate-to-vigorous PA 72% of the time. However, vector magnitude counts per minute (CPM) showed a strong correlation with criterion measures (r = 0.68 and 0.625 for SWAM and DLW and resting EE respectively). CONCLUSIONS: The currently available PAEE estimation equations from the manufacturer-provided software do not allow us to accurately measure PAEE or PA intensity with the wristworn GT3X+ in a population of older women. A high correlation of CPM from the GT3X+ with criterion measures indicates that the problem may lie in the available equations and cut points, not in the device itself.

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