The ESPEN Consensus Statement provides diagnostic criteria for malnutrition, aiming to establish a unified, internationally accepted definition. The consensus process involved a modified Delphi method, including email communications, face-to-face meetings, and ballots. The final criteria include two options for diagnosing malnutrition. Option one requires a body mass index (BMI) <18.5 kg/m². Option two requires unintentional weight loss (>10% of habitual weight or >5% over 3 months) combined with either reduced BMI (age-specific: <20 kg/m² for those under 70, <22 kg/m² for those 70 or older) or a low fat-free mass index (FFMI) (women <15 kg/m², men <17 kg/m²). Over 75% of ESPEN members agreed with these criteria. The statement emphasizes the importance of identifying individuals at risk of malnutrition using validated screening tools, followed by a diagnosis based on the criteria. It also highlights the need for clear diagnostic criteria to improve clinical care and nutritional practices. The consensus group decided not to favor either "malnutrition" or "undernutrition" as the preferred term, opting for "malnutrition" in this statement. The statement also outlines a conceptual tree of nutritional disorders, acknowledging the complex interactions between conditions. The consensus aims to provide a simple, comprehensive format for diagnosing malnutrition that is applicable in all clinical settings and independent of the underlying cause. The results of the consensus process are summarized in the Fact Box, which outlines the two alternative diagnostic criteria.The ESPEN Consensus Statement provides diagnostic criteria for malnutrition, aiming to establish a unified, internationally accepted definition. The consensus process involved a modified Delphi method, including email communications, face-to-face meetings, and ballots. The final criteria include two options for diagnosing malnutrition. Option one requires a body mass index (BMI) <18.5 kg/m². Option two requires unintentional weight loss (>10% of habitual weight or >5% over 3 months) combined with either reduced BMI (age-specific: <20 kg/m² for those under 70, <22 kg/m² for those 70 or older) or a low fat-free mass index (FFMI) (women <15 kg/m², men <17 kg/m²). Over 75% of ESPEN members agreed with these criteria. The statement emphasizes the importance of identifying individuals at risk of malnutrition using validated screening tools, followed by a diagnosis based on the criteria. It also highlights the need for clear diagnostic criteria to improve clinical care and nutritional practices. The consensus group decided not to favor either "malnutrition" or "undernutrition" as the preferred term, opting for "malnutrition" in this statement. The statement also outlines a conceptual tree of nutritional disorders, acknowledging the complex interactions between conditions. The consensus aims to provide a simple, comprehensive format for diagnosing malnutrition that is applicable in all clinical settings and independent of the underlying cause. The results of the consensus process are summarized in the Fact Box, which outlines the two alternative diagnostic criteria.