The minimum detectable change in areal BMD (aBMD) using DXA is ~1% for all types of scans. In order to confidently examine changes in BMD following interventions in young adults, study duration is 2 y. Whole body, LS vertebrae 1 to 4 (AP and lateral), left hip (total and FN) and forearm (non-dominant) will be measured using a Hologic 4500A fan-beam clinical densitometer at baseline, 1 and 2 y. For this test, RCT participants will wear standardized clothing (cotton pants and T-shirts). DXA is rapid, taking a total of 5-7 minutes x-ray time, and the low radiation (<10 uSV) will not exceed limits for x-ray exposure. Values will be compared to the Hologic normative databases and thus expressed as BMC and BMD along with Z-scores where applicable (from the National Health and Nutrition Examination Survey [NHANES] reference database) and from CaMos data. Quality control data will be monitored and maintained using a proprietary LS bone phantom (Hologic). To complement, tibia and forearm BMD will be measured at baseline, 1 and 2 y as well using the peripheral quantitative computed tomography technique (pQCT). Unlike most other common techniques for measuring BMD, a pQCT scan is able to measure volumetric bone mineral density and the geometry of the bone whereas DXA is only able to provide the areal bone mineral density. For this measurement we will examine sites ranging from 4 to 66% from the distal radius and tibia of the non-dominant side; the 4% site will provide for a trabecular rich region and the 66% will provide a cortical bone assessment, we will also examine the 14% and 38% sites of the tibia.