Development of new reference values for body composition by dual-energy x-ray absorptiometry in Canadian adults aged >45 years: results from the Canadian Longitudinal Study on Aging

Cut-off values for fat-free mass index (FFMI) and lean-mass index (LMI) are used as part of a nutritional review to help inform clinical decision-making. The cut-off values commonly used tend to be based on fixed reference values for males and females. Fixed cut-off values tend to only account for sex-specific differences in FFMI/LMI, even though it is now well known that both age and body mass index (BMI) have a large impact on both fat-free mass (FFM) and lean mass (LM). LM is more precise for measuring muscle mass than FFM. The ability to measure LM is hard due to the equipment needed; therefore, reference equations need to be created to estimate LM. The proposed research will produce a new reference value set by using data from the Canadian Longitudinal Study on Aging which are age, sex, and BMI-specific to allow for a more exact value of oddly low FFMI. This research will also create reference equations for the prediction of LM for use in clinical practice and future research.