Doctoral Dissertation Research: Thermogenesis and energetic costs in humans

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This doctoral dissertation project will examine the energetic cost of brown adipose tissue (BAT), a heat-producing tissue known to be activated under cold conditions, in 100 adults from a lower-latitude population. Research on BAT in adults has been relatively understudied, and this project will expand the available data and geographic scope for investigating BAT’s role in human heat production, energy allocation, and cold adaptation. The project will advance fundamental knowledge in human biology, and may also inform public health research on obesity and diabetes. In addition to the direct transmission of some data to study participants, project outcomes will be shared with the greater public through platforms such as social media, public talks, and publications in open-access journals. Furthermore, this study will foster research collaborations with local research assistants, who will develop STEM research skills and facilitate the smooth and culturally appropriate implementation of the project. BAT has been extensively studied in hibernating mammals and in human infants, but fewer studies have focused on its functions in adults. Researchers have suggested that BAT may have played a role in human evolution as an adaptive defense mechanism against chronic cold and that it may also be useful in reducing risks of metabolic diseases given its physiological effects on metabolism. In this study, BAT function will be examined in a lower-latitude population showing an average body size and shape that is morphologically best adapted to retain heat despite living in a warm region. BAT will be inferred by comparing metabolic rates and heat dissipation in the chest and shoulder area (main BAT location in adults) at room temperature and at mild cold exposure. Simultaneously, fasting glucose levels as well as respiratory quotients (a ratio determining metabolic substrates consumed) will be measured before and after BAT activation to determine BAT’s use of glucose. By determining the metabolic and heat-producing capabilities of BAT in the study population, this research will parse out how BAT may be a physiological reflection of cold adapted morphology and by extension how BAT may have played a role in the successful dispersal of humans into different ecological settings independent of their morphology. A better understanding of the energy consumption and glucose disposal of BAT can provide insight into its potential utility in weight gain and diabetes prevention. These potential health benefits of BAT activation are especially important for regions burdened by high rates of obesity and diabetes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.