PURPOSE OF REVIEW: This review aims to explain the causes, diagnosis, and treatment of malnutrition in hospitalized patients with inflammatory bowel disease (IBD), focusing on both adults and children. RECENT FINDINGS: Malnutrition is common among IBD patients, affecting up to 85% of individuals, and is linked to higher rates of illness, death, and longer hospital stays. Recent studies highlight the importance of early detection using tools like the Subjective Global Assessment (SGA) and handgrip strength tests. Nutritional interventions-such as exclusive enteral nutrition (EEN) and parenteral nutrition (PN)-have proven effective in inducing remission and improving patient outcomes, especially in pediatric Crohn's disease. New evidence suggests that optimizing nutrition before and after surgery, as well as using immunonutrition, may reduce postoperative complications. Early identification and management of malnutrition in hospitalized IBD patients may be important for improving clinical outcomes. Using appropriate nutritional screening tools and creating personalized nutrition plans can help with recovery, decrease hospital stays, and improve quality of life. Further research is needed to develop standard protocols for nutritional assessment and treatment in this patient population.