OBJECTIVE This study was undertaken to identify predictors of body weight change in nursing home patients with possible to severe dementia. METHODS For 24 weeks, 108 elderly residents of a nursing home were followed. Body weight was measured every 2 weeks. Other anthropometric characteristics, dietary intake, food behavior restrictions, psychological characteristics, medical status, and use of medicines were measured at baseline. Dietary intake was measured with a combined 3-day food record and by observations during the hot meals. Food behavior restrictions were measured following the classification of Berkhout. Dependency was measured by a questionnaire (Care Index Geriatrics), which measures restrictions in cognitive, physical, and social functioning. A generalized linear mixed effects model was used to investigate weight changes over time. The model was adjusted for age and sex. RESULTS During the follow-up period, 26% of the participants lost and 22% gained at least 2 kg of body weight. Dependency (beta = -0.11, 95% confidence interval [CI] = -0.21, -0.01) and decreased appetite (beta = -2.17, 95% CI = -4.32, -0.01) were significantly associated with body weight loss, whereas body mass index (beta = 2.25, 95% CI = 1.98, 2.51) and intake of fat (beta = 0.07, 95% CI = 0.01, 0.15) were predictors of weight gain. CONCLUSIONS Dependency, body mass index, intake of fat, and decreased appetite are significant predictors of body weight changes.