In this observational study, the investigators will examine the changes in body composition in HIV-infected subjects before and after initiation of HIV treatment, and look at the correlations with changes in cardiometabolic indices such as endothelial function and coronary calcium scoring.

The effects of lifestyle factors on body composition changes after antiretroviral therapy (ART) are unknown, and as such, investigators will use this prospective observational cohort to study relationships between lifestyle factors, including diet, physical activity and illicit drug use, with changes in body composition after ART. In addition, the effect of the body fat changes will be correlated to changes in cardiometabolic indices such as endothelial function and coronary calcium scoring.

Inclusion Criteria:

• HIV-1 infection as documented by any licensed ELISA test kit and confirmed by Western blot at any time prior to study entry. HIV-1 culture, HIV-1 antigen, plasma HIV-1 RNA, or a second antibody test by a method other than ELISA is acceptable as an alternative confirmatory test
• Provides written informed consent and is capable of reading and comprehending the informed consent
• Is not currently taking antiretroviral therapy and has never been on such treatments in the past. Exception would be for subjects who had been in the past on ≤30 days cumulative antiretrovirals, as long as these were stopped >6 months prior to study entry
• Is planning on starting antiretroviral therapy as part of routine clinic care

Exclusion Criteria:

• Pregnancy or lactation

Subjects will be primarily recruited from the practice of the investigator (the Special Immunology Unit (SIU) at University Hospitals Case Medical Center). All subjects seen at the Special Immunology Unit who meet the inclusion/exclusion criteria will be approached for study participation. Subjects who see physicians outside of the SIU may be eligible as well if they contact the study team and meet the inclusion criteria.