VISIT 2 Body composition and metabolic profiling After consuming a standardized meal the previous evening, participants will report to the Wellcome Trust Clinical Research Facility in a 10 hour fasted state at approximately 09.00. Participants will be weighed in light clothing and blood pressure will be measured. Thereafter, body composition will be determined using dual energy Xray absorptiometry (DXA) and resting metabolic rate (RMR) via ventilated hood and continuous gas collection. Following RMR, a catheter will be inserted into a forearm vein and a resting, fasted blood sample obtained to determine postprandial insulin sensitivity using the HOMA-IR index.