Before and after the cooling suit is turned on, body scans will be performed using a procedure called positron emission tomography (PET). These scans do not use radiation. Before the PET scans, the investigators will infuse radioactive tracer into an arm. These tracers have a low dose of radiation and will show us where the brown fat is and how active it is. One PET scan will be performed at room temperature, and the second scan will be performed after the cooling suit has been worn for 3 hours. Two additional scans using computed tomography (CT) will be performed at end of the study. CT scans are like an x-ray, and use radiation. The radiation dose in the CT scan is much higher than the tracers. When the CT scans are combined with the PET scans, we can separate brown fat from white fat.