Nutrition/Obesity
Measuring sarcopenic obesity in older adults: development of age and sex-specific fat mass to fat-free mass ratio (FM/FFM) percentile curves using data from the Canadian Longitudinal Study on Aging Chris Kim* Chris Kim Claire Cook Hailey Banack
Chris Kim, MPH, Claire Cook, MPH, Hailey Banack, PhD
Background: Fat mass to fat-free mass ratio (FM/FFM) measures the relative contribution of fat mass (kg) and fat-free mass (kg) within an individual; a higher FM/FFM indicates a greater proportion of fat mass relative to lean body mass. The objective of this work is to develop age- and sex-specific FM/FFM percentile curves for older adults as a measure of sarcopenic obesity.
Methods Baseline data from the Canadian Longitudinal Study on Aging (CLSA) Comprehensive cohort were used (n=28,791). FM/FFM was calculated as the ratio of total body fat mass (kg) to total body lean mass (kg) from Dual-Energy X-ray Absorptiometry (DXA) scan. Age and sex-specific FM/FFM weighted percentile curves for the 1st, 5th, 25th, 50th, 75th, 95th, and 99th percentiles were calculated using the LMS method. LMS provides a summary of the changing distribution of the measurement of interest by the three curves, lambda for the skewness (L), mu for the median (M), and sigma for the coefficient of variation (S). The weighted percentile curves were then plotted with age on the x-axis and FM/FFM on the y-axis for males and females, respectively.
Results: The maximum FM/FFM was approximately 0.77 at age 70 for males and approximately 1.14 at age 66 for females (Figure 1). The median FM/FFM values in the same age ranges were approximately 0.41 and 0.70 for males and females, respectively. For both males and females, FM/FFM tended to increase until 65-70 years of age and decreased thereafter. Females experience increases in FM/FFM at earlier ages and decline at faster rates than males.
Conclusions: On average, males tended to have lower FM/FFM and had generally slower decline in FM/FFM than females. These patterns are similar to previous findings among older adults from US and China. Further research on sex differences in sarcopenic obesity among older adults is warranted.
