HRRBAA: The metabolic cost of living among herders

Suny At Albany, Albany NY

Investigators

Abstract

The constrained total energy expenditure hypothesis suggests that in the face of high levels of physical activity the human body works to reduce the overall number of calories burned each day. However, the idea that humans live within a narrow metabolic range has not been broadly tested across climates and seasons. To further address this hypothesis, this high-risk research project will assess feasibility of measuring energy expenditure and brown adipose tissue activation in a highly active cold-climate population. The fundamental human biology research that would result from this effort will inform our understanding of how metabolism and brown adipose tissue relate to the obesity epidemic in the modern world. The research will support research training and mentoring for undergraduate and graduate students, international collaborations, and science outreach to local communities. Results will be disseminated in peer review journals as well as incorporated into undergraduate and graduate curricula at the University at Albany. Using the flex-heart rate and doubly labeled water methods, total energy expenditure (calories burned each day) will be measured during the herd round-up, which lasts roughly one week during the late fall. Physical activity levels (used to estimate and compare energy expenditures) and dietary intake will also be documented during this time. Resting metabolic rate, age, sex, body mass, body fat percentage, muscle mass, glucose levels, and cholesterol levels will be recorded for each subject. These data will be used to develop a metabolic profile, determining how many calories are used for different activities and during rest. Energy expenditure measurements will be compared to estimates to determine if herders expend fewer calories than expected, as hypothesized by the new constrained theory for human energy expenditure, or if the measurements reflect a higher energetic demand required by inhabiting a harsh environment. Finally, a new procedure employing a thermal imaging camera will be used to measure brown adipose tissue activation in the field. Typically, brown adipose tissue studies take place in clinical settings and require PET-CT scans; the procedure used in this study is more flexible for both researchers and study participants in the field. This project will act as a spring board for developing a longitudinal study examining seasonal impacts on total energy expenditure, physical activity levels, brown adipose tissue activation, and applications for addressing the obesity epidemic.