For a study, researchers sought to compare changes in dual x-ray absorptiometry (DXA) derived body composition in ICU survivors in the year following discharge to population controls. Using prospective observational data, changes in hip and spine DXA estimated lean and fat mass between ICU discharge and 1-year follow-up were calculated and compared using multivariable linear regression to age-sex-height matched controls from the Geelong Osteoporosis Study. About 64 participants were included, with a median age of 68.8 years [IQR 60.8, 74.6], ICU length of stay of 6.5 days [IQR 4, 9], and mechanical ventilation duration of 87 hours [IQR 47, 143]. ICU survivors had higher annual increases in lean (+0.92 kg; 95% CI 0.67 to 1.18, P<0.01) and fat mass (+2.50 kg, 95% CI 1.94 to 3.05, P<0.01) mass than controls. At 1 year, the ICU group had lower lean mass (−0.96 kg, 95% CI -1.91 to −0.01; P=0.047) and higher fat mass (6.79 kg, 95% CI 4.55 to 9.03; P<0.001). Adult ICU patients on mechanical ventilation gained lean mass in the year following critical illness, but not to the level of matched population-based peers. More research was needed to understand the factors associated with, and the effect of, increasing muscle mass and decreasing fat mass in the year following critical illness.