After considering the plethora of research variables and the limitations of BMI, it is worth considering if BMI is the best indicator of nutritional status as it pertains to lung function (FEV1). Research is also starting to question if lung function is higher in leaner patients of the same BMI. If so, should we consider the ratio of fat mass to FFM as a nutritional indicator instead of BMI in this critical patient population? Lastly, the blooming prevalence of obesity in the adult and pediatric CF population, as well as the rapid increase of patients diagnosed with CFRD is concerning (Kelly & Moran, 2013). Accordingly, what is the relationship between excess body fat and CFRD? Furthermore, what evidence is available to say that the current medical nutritional therapy used in practice is contributory to the increased rate in excess body fat and/or CFRD? The remainder of this review shines light on these questions by analyzing the current research and a relevant case study to reveal implications in practice. I then offer suggestions for guidelines and future research.