Brown fat activity determined by infrared thermography and thermogenesis measurement using whole body calorimetry (BRIGHT Study).

To assess BAT activity in humans at a population level, infrared thermography (IRT) represents a safe, readily repeatable and affordable alternative to 18F-FDG-PET. Building upon a previously proposed method by our laboratory, we further refined the image computational algorithm to quantify BAT activation in the cervical-supraclavicular (C-SCV) region of healthy young men under thermo-neutral and cold exposure conditions. Additionally, we validated the whole-body calorimeter (WBC) in reliably measuring cold-induced thermogenesis. The temperature gradient between C-SCV-deltoid regions, and the corresponding difference in heat power output, increased upon cold air exposure relative to thermo-neutral conditions (by 74.88 %, p<0.0001; and by 71.34 %, p<0.0001 respectively). Resting and cumulative energy expenditure (EE) rose significantly (by 13.14 % and 9.12 % respectively, p=0.0001) while positive correlations between IRT measures and EE were found with cold air exposure (percentage change in heat power gradient between ROI and deltoid, cold air: r(2)=0.29, p=0.026, Pearson's correlation). IRT and WBC can be used to study BAT activation. The refined algorithm allows for more automation and objectivity in IRT data analysis, especially under cold air exposures.

Gross and relative energy cost of domestic household activities in Asian men.

BACKGROUND/OBJECTIVES: Obesity is on the rise and participation in exercise has declined. Domestic household activities may help meet the recommended daily physical activity levels. This study aimed to measure the energy costs of household activities among Asian males. SUBJECTS/METHODS: This was a randomised cross-over study conducted in a whole-body calorimeter. The energy costs of 14 domestic household activities, divided into two studies, were measured in 10 healthy Asian males. Participants' weight, height, body composition and basal metabolic rate were measured on the first test visit. A standard breakfast was served and participants rested for an hour before the measurement of energy costs of domestic household activities. During the measurements, each activity was performed for 20 min, and participants rested for 30 min between activities. RESULTS: The mean energy costs of domestic household activities ranged from 5.92 to 11.97 kJ/min, which were significantly different between activities (repeated measures analysis of variance, P<0.001). When expressed as metabolic equivalents (METS), all domestic household activities were classified as low-intensity physical activities. Actual METS (METSactual) were significantly different to standard METS of eight activities, which may be partly explained by the universal assumption of 3.5 ml O2/kg/min made during the calculation of METS in the Asian population. CONCLUSIONS: The energy costs of a range of domestic household activities reported in this study may assist in the planning of physical activities among Asians to meet national physical activity guidelines.