Total daily energy expenditure (“total expenditure”) reflects daily energy needs and is a critical variable in human health and physiology, but its trajectory over the life course is poorly studied. We analyzed a large, diverse database of total expenditure measured by the doubly labeled water method for males and females aged 8 days to 95 years. Total expenditure increased with fat-free mass in a power-law manner, with four distinct life stages. Fat-free mass–adjusted expenditure accelerates rapidly in neonates to ~50% above adult values at ~1 year; declines slowly to adult levels by ~20 years; remains stable in adulthood (20 to 60 years), even during pregnancy; then declines in older adults. These changes shed light on human development and aging and should help shape nutrition and health strategies across the life span.

As the global coronavirus (COVID-19) pandemic unfolds, more than 90% of U.S. adult residents are confined to their homes, with restaurants, shops, schools, and workplaces shut down to prevent disease spread. Although it is a priority to mitigate the immediate impact, one area of great concern is the long-term effects of this pandemic on weight management in adults. As evident from previous research, small changes in body weight in relatively short periods can become permanent and lead to substantial weight gain over time (1). Considering that the current situation could last a total of several months, this extended home confinement could exacerbate the problem of obesity in adults by substantially contributing to or exceeding annual weight gain.

Cross-sectional analyses have shown increased obesogenic behaviors and a potential for weight gain during COVID-19 related peak-lockdown (March–May 2020), but longitudinal data are lacking. This study assessed longitudinal changes in body weight and lifestyle behaviors in the US adults during the pandemic. Methods: We used Qualtrics survey to collect self-reported data on body weight, dietary, physical activity, and psychological variables (n = 727) during the peak-lockdown (April/May) and at post-lockdown (September/October). Peak-lockdown weight data were categorized based on the magnitude of weight gained, maintained, or lost, and behavioral differences were examined between categories at two time points. Results: Body weight increased (+0.62 kg; p < 0.05) at the post-lockdown period. The body mass index also increased (26.38 ± 5.98 kg/m2 vs. 26.12 ± 5.81 kg/m2; p < 0.01) at the post-lockdown period vs. peak-lockdown period. Close to 40% of participants reported gaining either 1–4 lbs or >5 lbs of body weight during the peak-lockdown, while 18.2% lost weight. Weight-gainers engaged in riskier dietary behaviors such as frequent ultra-processed food intake (p < 0.01) and snacking (p < 0.001), were less active, and reported high stress and less craving control during peak-lockdown. Of those gaining >5 lbs, 33% continued to gain weight after the lockdown eased, while 28% maintain higher body weight. In weight-gainers, takeout meal frequency increased, and high ultra-processed food intake and stress, and low craving control continued to persist after the lockdown eased. Conclusion: We show that the COVID-19 lockdown periods disrupted weight management among many Americans and that associated health effects are likely to persist.

The Deltatrac Metabolic Monitor (DTC), one of the most popular indirect calorimetry systems for measuring resting metabolic rate (RMR) in human subjects, is no longer being manufactured. This study compared five different gas analysis systems to the DTC. Resting metabolic rate was measured by the DTC and at least one other instrument at three study sites for a total of 38 participants. The five indirect calorimetry systems included: MedGraphics CPX Ultima, MedGem, Vmax Encore 29 System, TrueOne 2400, and Korr ReeVue. Validity was assessed using paired t-tests to compare means while reliability was assessed by using both paired t-tests and root mean square calculations with F tests for significance. Within-subject comparisons for validity of RMR revealed a significant difference between the DTC and Ultima. Bland-Altman plot analysis showed significant bias with increasing RMR values for the Korr and MedGem. Respiratory exchange ratio (RER) analysis showed a significant difference between the DTC and the Ultima and a trend for a difference with the Vmax (p = 0.09). Reliability assessment for RMR revealed that all instruments had a significantly larger coefficient of variation (CV) (ranging from 4.8% to 10.9%) for RMR compared to the 3.0 % CV for the DTC. Reliability assessment for RER data showed none of the instrument CV's were significantly larger than the DTC CV. The results were quite disappointing, with none of the instruments equaling the within person reliability of the DTC. The TrueOne and Vmax were the most valid instruments in comparison with the DTC for both RMR and RER assessment. Further testing is needed to identify an instrument with the reliability and validity of the DTC.Correspondence and request for reprints: Dr. Dale Schoeller,

We hypothesized that if airway remodeling is related to duration of asthma, that when matched for severity, the airways of older adults should show greater alterations than the airways of younger adults. Using standard morphometric techniques, we compared airways with basement membrane perimeters (Pbm) between 2 and 10 mm from young individuals who died of asthma (n = 14, range 17-23 yr), and older individuals with fatal asthma (n = 13, range 40-49 yr). Comparisons were also made with normal airways from age-matched adults. Wall area was increased in old individuals with fatal asthma compared with young individuals with fatal asthma, primarily due to greater adventitial area, whereas wall area in young individuals with fatal asthma was not different from control subjects. Within muscle bundles the connective tissue matrix was increased around individual cells in individuals with asthma, unrelated to age. After adjustment for this change, smooth muscle area in both asthma groups was still greater than in age-matched control subjects, in old individuals with fatal asthma 4-fold greater (p = 0.04), and in young individuals with fatal asthma 2-fold greater (p = 0.03). Airway narrowing was increased in old versus young individuals with fatal asthma, with both groups more narrowed than control subjects. Intralumenal obstruction and subepithelial collagen in the two asthma groups were significantly greater than in control subjects, but there was no age effect. These data provide support for the hypothesis that there is an increase in airway wall area, including smooth muscle, and airway narrowing with increasing duration of severe asthma or with older age. The observation that total wall thickness was not greater in young individuals with young fatal asthma than in control subjects suggests that factors other than airway wall geometry contribute to the pathogenesis of fatal attacks in this age group.