Background: Body composition is an important indicator of nutritional status and health. How body composition changes during 12 mo of breastfeeding in HIV-infected women receiving antiretroviral therapy (ART) is unknown.

Objective: We assessed whether HIV or food insecurity was associated with adverse postpartum body-composition changes in Ugandan women.

Design: A cohort of 246 women [36.5% of whom were HIV positive (HIV+) and were receiving ART] were followed to 12 mo postpartum. Repeated measures included weight, fat mass, fat-free mass, midupper arm circumference, triceps skinfold thickness [which allowed for the derivation of arm muscle area (AMA) and arm fat area (AFA)], breastfeeding, and individual food insecurity. Longitudinal regression models were constructed to assess associations between HIV and food insecurity and changes in body composition over time.

Results: At baseline, HIV+ women compared with HIV-negative women had a higher mean ± SD food-insecurity score (11.3 ± 5.5 compared with 8.6 ± 5.5, respectively; P < 0.001) and lower AMA (40.6 ± 5.7 compared with 42.9 ± 6.9 cm3, respectively; P = 0.03). Participants were thin at 1 wk postpartum [body mass index (BMI; in kg/m2): 22.9 ± 2.9]. From 1 wk to 12 mo, the weight change was −1.4 ± 4.4 kg. In longitudinal models of body-composition outcomes, HIV was not associated with body composition (all P > 0.05), whereas food insecurity was inversely associated with body weight and BMI at 6, 9, and 12 mo and with AFA at 6 and 12 mo (all P < 0.05). At 6 mo, every 1-unit increase in the food-insecurity score was associated with a 0.13-kg lower body weight (P < 0.001) and a 0.26-cm3 lower AFA (P < 0.01).

Conclusions: Body-composition changes are minimal during lactation. HIV is not associated with body composition; however, food insecurity is associated with changes in body composition during lactation. This trial was registered at clinicaltrials.gov as NCT02922829 and NCT02925429.