Comparison of Body Mass Index Range Criteria and Their Association with Nutrition-Related Risk: A Cross-Sectional Study in Polish Older Adults.

BACKGROUND The use of appropriate reference values for body mass index (BMI) indicators in the elderly population is crucial when assessing the risk of malnutrition. The aim of the present study was to compare the distribution of BMI according to the ranges proposed by the World Health Organization (WHO) and the Committee on Diet and Health (CDH), and to examine their correlation with nutrition-related risk as assessed by the Geriatric Nutritional Risk Index (GNRI) in older adults. MATERIAL AND METHODS The study involved 185 patients hospitalized in the geriatric ward. Anthropometric measurements were performed in accordance with the applicable standards. GNRI was calculated to assess the risk of mortality and morbidity related to malnutrition. RESULTS The no nutrition-related risk group had a median BMI of 28.5 kg/m, while the nutrition-related risk group showed a significantly lower median BMI of 22.8 kg/m² (P<0.0001). Under CDH BMI criteria, 75% of underweight participants had a nutrition-related risk, compared with 6.3% under WHO criteria. Among those with normal weight, 81.3% (WHO) and 22.9% (CDH) were at risk. For excess body weight, the risk was 12.5% (WHO) and 2.1% (CDH). CONCLUSIONS This study highlights significant discrepancies between BMI classification systems by WHO and CDH for older adults. WHO criteria may underestimate underweight cases and overestimate excess body weight. CDH, being more sensitive to underweight detection and strongly correlated with GNRI-based risks, proves more effective for assessing nutritional status. Tailored BMI guidelines for older adults are essential for accurate health assessments and improved care.