Will Relative Fat Mass Replace BMI?

Years ago we, at FitForce, stopped teaching body fat analysis. The skin-fold technique of evaluating body composition was taught to countless classes over the years and some agencies (my former included) had a “body fat standard” for academy entrance and graduation. Two issues primarily moved us away from teaching the technique: some early court cases under Title I of the American’s with Disabilities Act (1990) resulted in decisions supporting the notion of obesity as a disability (it’s a long story, but Congress closed the door on those challenges) and; perhaps more importantly, we were unable to identify a percentage of body fat that consistently and with a high degree of certainty was related to or predicted successful physical job task performance.

We have however continued to discuss the health risks associated with overweight or obesity. Body Mass Index (BMI) has been a popular choice in several fields (Use this table to find your BMI.) Because BMI does not consider lean body mass, age, or gender, it is necessary to include a second factor: waist circumference or waist/hip ratio, in the discussion of one’s relative risk of metabolic or other diseases. For the record, males should keep waist measurement to 40”,< and females 36”,<.

Recently, investigators at Cedars-Sinai Medical Center published the results of their research into a new technique that focuses on height and waist circumference to determine relative fat mass (RFM).

Males: 64 - (20 x Height/Waist Circumference) = RFM

Females: 72 - (20 x Height/Waist Circumference) = RFM

In the study, measurements were taken in meters. Any research to fine-tune body analysis is an important task; according to the Centers for Disease Control, over 40% of adult Americans (93 million!) are obese.

A good overview of the study can be found here.

If you’d like the full study, you can download it.

If you’re still doing body fat analysis, of any kind, compare the three techniques and tell us about your experience.

Stay Safe, Stay Strong