Multivariable modeling was performed using data from the Nutrition Care in Canadian Hospitals Study, identifying factors independently associated with weight change, and specifically weight loss, prior to, during, and following acute hospitalization in older patients (≥65y, n=503). Male gender (OR=1.83, 95% CI 1.23-2.73) and oral nutrition supplement use (OR=2.1, 95% CI 1.31-3.36) were associated with self-reported weight loss (n=445, R2=0.06). Higher BMI (β=-0.2, p=0.001), occurrence of adverse events (β=-0.15, p=0.008), mean intake <75% of meals during admission (β=-0.19, p=0.001), and antibiotic use during admission (β=-0.11, p=0.049) were significantly associated with weight loss during admission (n=290, R2=0.14). Post hospital weight loss was associated with a poor self-reported appetite at follow-up (OR=3.82, 95% CI 2.1-6.97), eating with others never or rarely (OR=2.48, 95% CI 1.31-4.69), and having been admitted to a surgical ward (OR=1.86, 95% CI 1.03-3.35) (n=279, R2=0.16).