The objective of this study was to compare changes in body composition between ritonavir-boosted atazanavir ( ATV/r ) and ritonavir-boosted lopinavir ( LPV/r ) over 96 weeks using data from a substudy of CASTLE , which compared once-daily ATV/r with twice-daily LPV/r , both in combination with tenofovir disoproxil fumarate/emtricitabine in treatment-nave patients with HIV-1 infection .