Adherence to antiretroviral therapy (ART) is critical for reducing HIV/AIDS morbidity and mortality. Food insecurity (FI) is emerging as an important barrier to adherence to care and treatment recommendations for people living with HIV (PLHIV), but this relationship has not been comprehensively examined. Therefore, we reviewed the literature to explore how FI may impact ART adherence, retention in medical care, and adherence to health care recommendations among PLHIV. We found data to support FI as a critical barrier to adherence to ART and to other health care recommendations among HIV-infected adults, HIV-infected pregnant women and their HIV-exposed infants, and child and adolescent populations of PLHIV. Associations between FI and ART non-adherence were seen in qualitative and quantitative studies. We identified a number of mechanisms to explain how food insecurity and ART non-adherence may be causally linked, including the exacerbation of hunger or ART side effects in the absence of adequate food and competing resource demands. Interventions that address FI may improve adherence to care and treatment recommendations for PLHIV.