Body Composition assessment in morbidly obese bariatric surgery patients, a prospective longitudinal cohort study.

Patients undergoing primary sleeve gastrectomy surgery (metabolic weight loss surgery) for obesity treatment in Melbourne, VIC at private and 1 public hospital, will undergo body composition analysis and functional assessments within 1 month prior to surgery and repeated again at 12 months post-operatively. DEXA scans, bioimpedance analysis and ultrasound measures of body composition will be performed at study visits by 1 study investigator. All other clinical data (weight, waist circumference, height, physical activity level, bloods) will either be collected on the day of study visit by the study investigator from the patient or their hospital files (no additional measurements outside of routine clinical care will be collected for the purpose of the study). The anticipated time needed to complete DEXA scan (30 mins), bioimpedance analysis (20 minutes) and ultrasound (20 minutes) measures of body composition is a total of 70 minutes per study visit. The DEXA scan will involve participants wearing light clothing, with metal such as jewellery removed, laying down on a bed while the scanner arm passes over their body, a non-invasive low dose x-ray scan is performed to produce a total body scan. For ultrasound measurements, participants are asked to wear loose clothing that allows easy access to thighs, upper arm and abdomen. They will be laying down on a hospital bed with their head elevated 30 degrees. The study investigator will then undertake a non-invasive ultrasound image protocol using a probe that uses sound waves to create real time images of body tissue at the upper arm, forearm, mid-thigh and umbilicus. Following the ultrasound, the participants will remain laying on the hospital bed and the study investigator will then apply 2 electrodes on participants right hand and 2 electrodes on participants right foot. 3 separate bioimpedance scans will be conducted 5 minutes apart. The bioimpedance scan involves a very low voltage electrical current that is applied to the body from the electrodes, to measure resistance and reactance of the body. All study visits will be located at Monash University Alfred Hospital campus in Melbourne, VIC.