Objective: The aim of this study was to investigate the prevalence of risk of malnutrition (RoM) in an orthopedic and traumatology patient cohort with a broad range of ages. In addition to the classical indicators for risk assessment (low body mass index, weight loss, and comorbidity), this study aimed to analyze the effects of lifestyle factors (eating pattern, smoking, physical activity) on RoM. Methods: The prospective cohort study included 1053 patients in a level 1 trauma center in Germany. RoM was assessed by Nutritional Risk Screening (NRS) 2002 and for the elderly additionally by Mini Nutritional Assessment (MNA). Age-dependent risk factors identified in univariate statistical analysis were used for multivariate logistic regression models. Results: The prevalence of patients at RoM (NRS >= 3) was 22%. In the three age categories (= 70 y), loss of appetite, weight loss, number of comorbidities, drugs and gastrointestinal symptoms significantly increased RoM in univariate statistical analysis. In patients ages >= 70 y, several disease- and lifestyle-related factors (not living at home, less frequent consumption of vegetables and whole meal bread, low physical activity, and smoking) were associated with RoM. Multivariate logistic regression model for the total study population identified weight loss (odds ratio [OR], 6.09; 95% confidence interval [CI], 4.14-8.83), loss of appetite (OR, 3.81; 95% CI, 2.52-5.78), age-specific low BMI (OR, 1.87; 95% Cl, 1.18-2.97), number of drugs taken (OR, 1.19; 95% Cl, 1.12-1.26), age (OR, 1.03; 95% Cl, 1.02-1.04), and days per week with vegetable consumption (OR, 0.938; 95% CI, 0.89-0.99) as risk factors. Conclusion: Malnutrition in trauma and orthopedic patients is not only a problem related to age. Lifestyle-related factors also contribute significantly to malnutrition in geriatric patients. (C) 2017 Elsevier Inc. All rights reserved.