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OBJECTIVE: The role of brown adipose tissue (BAT) in infant metabolism remains poorly understood, primarily because of the inherent limitation of positron emission tomography/computed tomography imaging to measure BAT, which is not suitable for infants. The aims of this method development study were to assess the feasibility, intra-rater reliability, interscan repeatability, and physiological relevance of measuring BAT in infants using magnetic resonance imaging (MRI). METHODS: A total of 10 nonsedated infants (mean age, 22.6 [1.3] days old) completed two 3-T MRI exams using chemical-shift-encoded water-fat scans 6.2 (2.8) days apart. Candidate BAT voxels in the supraclavicular region were identified based on fat signal fraction (FSF). The volumes of BAT depots were manually traced, and FSF was calculated. Whole-body fat mass was determined using dual-energy x-ray absorptiometry. RESULTS: Images were successfully obtained from 19 of 20 (95%) attempted scans. The mean BAT volume was 5.41 (SD 1.1) cm(3), and the mean FSF was 16.41% (SD 3.3%). Intra-rater analysis showed good reliability with no systemic bias (proportional bias for volume: p = 0.19; FSF: p = 0.30). Test-retest for interscan repeatability was good (intraclass correlation coefficients for volume: 0.92, p = 0.001 and intraclass correlation coefficients for FSF: 0.93, p < 0.001). FSF was inversely related to fat-free mass (r = −0.69, p = 0.03). CONCLUSIONS: This method development study supports the use of MRI to obtain reliable and quantitative measurements of BAT volume in infants.

OBJECTIVE The aim of this study is to characterize changes in body composition during pregnancy in women with obesity. METHODS Fifty-four healthy women with obesity (class 1, 30-34.9 kg/m2 : n = 25; class 2, 35-39.9 kg/m2 : n = 21; class 3, ≥ 40.0 kg/m2 : n = 8) expecting a singleton pregnancy were studied. Body composition was measured in early pregnancy (13-16 weeks), midpregnancy (24-27 weeks), and late pregnancy (35-37 weeks) using air displacement plethysmography, stable isotopes, and skinfold thickness measurements. Fasting glucose, insulin, and leptin were measured. RESULTS The gain in fat-free mass was lower in the second trimester compared with the third (2.7 ± 0.2 to 5.3 ± 0.2 kg; P

OBJECTIVE: Stay-at-home orders in response to the coronavirus disease 2019 (COVID-19) pandemic have forced abrupt changes to daily routines. This study assessed lifestyle changes across different BMI classifications in response to the global pandemic. METHODS: The online survey targeting adults was distributed in April 2020 and collected information on dietary behaviors, physical activity, and mental health. All questions were presented as "before" and "since" the COVID-19 pandemic. RESULTS: In total, 7,753 participants were included; 32.2% of the sample were individuals with normal weight, 32.1% had overweight, and 34.0% had obesity. During the pandemic, overall scores for healthy eating increased (P < 0.001), owing to less eating out and increased cooking (P < 0.001). Sedentary leisure behaviors increased, while time spent in physical activity (absolute time and intensity adjusted) declined (P < 0.001). Anxiety scores increased 8.78 ± 0.21 during the pandemic, and the magnitude of increase was significantly greater in people with obesity (P ≤ 0.01). Weight gain was reported in 27.5% of the total sample compared with 33.4% in participants with obesity. CONCLUSIONS: The COVID-19 pandemic has produced significant health effects, well beyond the virus itself. Government mandates together with fear of contracting the virus have significantly impacted lifestyle behaviors alongside declines in mental health. These deleterious impacts have disproportionally affected individuals with obesity.

OBJECTIVE This study aimed to identify factors that may predispose women to excess gestational weight gain (GWG). METHODS Seventy-two healthy women with obesity (30 class I, 24 class II, 18 class III) expecting a singleton pregnancy were studied at 13 to 16 weeks gestation. Energy expenditure (EE) was measured during sleep (SleepEE, average EE from 0200-0500 hours) in a whole-room calorimeter, and total daily EE (TDEE) over 7 days using doubly labeled water. Glucose, insulin, thyroid hormones, and catecholamines were measured. RESULTS Body composition explained 70% variability in SleepEE, and SleepEE accounted for 67% to 73% of TDEE. Though there was no evidence of consistent low metabolism, there was considerable variability. Low SleepEE was associated with insulin resistance and low triiodothyronine concentrations (both P = 0.01). Physical activity level was 1.47 ± 0.02. For women with SleepEE within 100 kcal/d of their predicted EE, TDEE was significantly less than the estimate (2,530 ± 91 vs. 2,939 kcal/d; P

Background Women with obesity are at increased risk for excess gestational weight gain. Studies in non-pregnant women suggest that the etiology of weight gain may be different between African-Ameri...