The results of this study suggested that household food insecurity and women dietary diversity were significantly associated with Undernutrition (BMI < 18.5) among women on ART independent of nutritional support, anemia, duration of ART, CD4 level, TB and other factors (AOR = 1.85, 95% CI: 1.98, 2.86 and AOR = 1.19, (95% CI: 1.08, 1.75), respectively. The gene discussed is CD4; the disease is anemia (phenotype).