 Study hypotheses: 1 The substitution of TDF for d4T or ZDV in patients with HIV lipoatrophy will result in an increase in mitochondrial DNA content in fat, skeletal muscle, and peripheral blood mononuclear cells PBMCs, which in turn will lead to an improvement in mitochondrial function as assessed by electron transport chain ETC and oxidative phosphorylation pathway OXPHOS activity. The latter should lead to a decrease in fat apoptosis and in mitochondrial and lipid oxidative damage biomarkers. 2 Supplementation with uridine via NucleomaxX will increase mtDNA content in adipose tissue and increase body fat content. 