Pneumonia remains an important cause of morbidity and mortality among children in low- and middle-income countries. Poor outcomes are associated with undernutrition. Nutritional supplementation may be beneficial. We examined the effect of supplementation with lipid-based ready-to-use therapeutic food (RUTF) on the body composition of children with severe pneumonia. Non-severely malnourished children (6-59 months) with severe pneumonia enrolled into the Children's Oxygen Administration Strategies and Nutrition trial in Uganda and Kenya, and randomized to receive a diet supplemented with RUTF (500 Kcal/day) for 56 days versus usual diet alone (control) were included. We assessed arm anthropometry and bioimpedance analysis at admission and days 28, 90, and 180 of follow-up. We used mixed effects linear regression to compare body composition between groups. We included 737 participants (369 in intervention
368 in control group). The median age was 16 months (IQR
9, 26), and 58.1% were male. Overall, baseline mean arm fat area (AFA), arm muscle area, and arm muscle circumference were 5.8 ± 1.8 cm2, 11.6 ± 2.3 cm2, and 12.3 ± 1.2 cm2, respectively. The mean fat mass and fat-free mass calculated in 116 participants were 5.5 ± 1.5 kg and 5.5 ± 1.5 kg, respectively. There were modest increases in most body composition parameters. RUTF significantly increased AFA at days 28 and 90 but not at day 180 (P-value = .03, .02, and .99, respectively). RUTF did not change other body composition parameters. Despite initial increases in AFA, RUTF did not change the body composition of children with severe pneumonia.