RFM helps spot adults with high body fat percentage

Relative fat mass (RFM) accurately identifies people with an elevated body fat percentage (BF%), but it is not as accurate as dual energy x-ray absorptiometry (DXA) in estimating BF%, reports a Chile study. 

A total of 270 healthy participants (145 men and 125 women) were included in this study. Their body composition was examined using DXA.  

The authors assessed anthropometric measurements to calculate RFM and BMI and obtained receiver operating characteristic (ROC) curves to evaluate the sensitivity and specificity of both RFM and BMI. They also performed Bland–Altman analysis between BF% measured by DXA and predicted BF% derived from RFM to assess validity. 

Finally, the authors calculated Pearson’s correlation coefficients to examine the relationship between BMI, RFM, and DXA. 

The cutoff for elevated BF% for RFM was ≥22.7 percent for men and ≥32.4 percent for women, while the cutoff for BMI was ≥24.4 kg/m2 for men and ≥24.1 kg/m2 for women. The area under the ROC curve between RFM and BMI did not differ significantly in men (0.970 vs 0.959; p=0.420) and in women (0.946 vs 0.942; p=0.750). 

Notably, the estimation bias was more noticeable in men than in women in the Bland–Altman analysis. 

“RFM may be an alternative method useful in primary care to select individuals for lifestyle counseling and in research to select patients for epidemiological studies,” the authors said.