The Limitations of Body Mass Index (BMI) as an Obesity Assessment Scale and the Implications for Practice: A Nursing Perspective

Rising obesity rates have a significant impact on morbidity, mortality and subsequent delivery of health services globally. Therefore accurate assessment of individual weight status is vital (Carpenter et al. 2013). Although, frequently used in clinical practice and research, the ability of the body mass index (BMI) to accurately assess obesity in individuals has been much criticised. Raising awareness among nursing staff of the limitations of BMI is important. By understanding the various inadequacies, the use of BMI as an assessment tool for obesity, and thereby a proxy measure of metabolic risk (Tchernof & Després 2013), nurses will be able to apply the scale with discretion to determine a truer assessment of health risk for the individual. From a literature search (CINAHL, Medline and PubMed) three themes that emerged. That BMI had limited applicability due to: an inability to distinguish percentage body fat from total weight; reduced sensitivity in the intermediate ranges of the scale and an inability to differentiate location and type of adiposity. Based on these three limitations, this review documents how obesity assessment outcomes in practice can be incorrect, specifically across different ethnic, gender and lifespan groups. While consensus was not reached in the literature to cease its use in practice, several authors promote amendments to ranges and/or the inclusion of other anthropometric measures to increase detection rates. However, recommending a change to practice is beyond the scope of this review.