 This will be cohort study design with both qualitative and quantitative methods of data collection. The investigators are aiming to study 64 HIV positive children as healthy controls either initiating ART or already on ART and 86 malnourished HIV infected children on ART or naïve initiating ART and RUTF aged between 6 months to 12 years. Primary carers will be asked to provide informed consent whereby the children and primary carers will be enrolled into the study and followed up for 12 weeks. 