This Study is focused on the interaction between resting metabolic rate (RMR), physical activity (PA), and thyroid hormones (TH). TH controls almost all the cell activities of the body so, it is known as one of the major regulatory hormones. This is the reason for individuals who suffer from thyroid disorders show abnormal metabolism. Recently it was suggested that interindividual variations in thyroid hormone levels also influence daily physical activity.
In this study, investigators will recruit adult females with a BMI ≥18.5. After the screening process, eligible volunteers will undergo certain measurements including body composition, resting metabolism daily physical activity, thyroid hormone levels, and total energy expenditure. The investigators will access the changes in resting metabolism and daily physical activities with the differences in thyroid hormone levels.
Study Type
OBSERVATIONAL
Enrollment
42
Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences
Shenzhen, Guangdong, China
Body weight
Subjects will be asked to fast overnight and weight will be measured using a calibrated Seca body weight scale first thing in the morning on subjects wearing light clothes and no shoes.
Time frame: Measurements will take at the first day of the visit
Height
Measured by seca 217 stable stadiometer. Subjects wearing no shoes.
Time frame: Measurements will take at the first day of the visit
Waist and Hip circumferences
Waist and Hip circumferences will be measured using a whole body laser scanner.
Time frame: Measurements will take at the first day of the visit
Fat mass
Fat mass will be measured by Magnetic Resonance Imaging (Shanghai united imaging, uMR 790 ) or DXA (Hologic).
Time frame: Measurements will take at the first day of the visit
Far free mass
Fat free mass will be measured by Bioimpedance Analysis (Tanita, MC-980) or DXA (Hologic).
Time frame: Measurements will take at the first day of the visit
Bone mass
Bone mass will be measured by DXA (Hologic).
Time frame: Measurements will take at the first day of the visit
Resting Metabolism
Resting energy expenditure will be measured using indirect calorimetry via a respiratory hood system (Cosmed). The subject attends the lab after an overnight fast. The person lies down on a flatbed and the hood is placed over their head. Metabolic rates (oxygen consumption and CO2 production) are monitored for 30 minutes. Calorimeters will be assessed with a turbine test to ensure the accuracy of measurements. Validation via an alcohol burn will be performed monthly.
Time frame: Measurements will take at the first day of the visit.
Physical activity
Physical activity of the participants will be recorded using GT3X accelerometer worn near the hip for a consecutive period of 14 days. The monitor should not be worn while bathing or swimming. The first day is discarded along with any day where the wear time is less than 10 hours. For a valid measure, the goal is to get at least 2 weekday and 2 weekend days.
Time frame: Measurements last for 14 days
Thyroid hormone
Nurses will collect the blood samples on day 1. Levels of circulating thyroid hormones will be measured using radio immunoassay.
Time frame: Blood samples will collect at the first day of the visit.
Resting Metabolism
The whole room calorimeter/metabolic chamber (OMNICAL, Maastricht instrument) will be used to measure resting metabolic rate. The metabolic chamber is a sealed room with a continuous gas supply (CO2- 0.80×10-2, O2 -18.00×10-2), providing subjects with 24-hour energy expenditure data. The total energy expenditure of the subjects in MJ/day was plotted against time in 30-minute intervals over 24 hours. The lowest and most stable energy expenditure during sleep time was considered the RMR of the subjects, which occurred from 2:00 am to 5:00 am.
Time frame: measurements will take at the first day of visit
Total energy expenditure
Total energy expenditure (TEE) will be measured using the DLW method. Urine samples from all participants in the DLW subset will be stored at -20 oC and analyzed in the laboratory of Dr. John Speakman at the Shenzhen Institute of Advanced Technology, Chinese Academy of sciences. Isotopes will be measured in a benchtop near-infrared isotope gas analyzer, and mean CO2 production will be calculated from isotope ratios using the recently derived equation (Speakman et al 2021: Cell reports medicine). TEE will then be calculated using mean CO2 production using the Weir equation.
Time frame: Measurements take for 14 days
Total energy expenditure
Total energy expenditure will be measured using the whole room calorimeter / metabolic chamber (OMNICAL, Maastricht instrument). The metabolic chamber is a sealed room with a continuous gas supply (CO2- 0.80×10-2, O2 -18.00×10-2), providing subjects with 24-hour energy expenditure data. The total energy expenditure was calculated by averaging the chamber's gaseous exchange using a 24-hour time window between 11.30 am and the next day around 3.00 pm.
Time frame: Measurements take at the first day of the visit
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