What is RFM and Why Should You Care?
Relative Fat Mass (RFM) is a body composition metric designed to estimate body fat percentage more accurately than BMI. Unlike BMI, which only considers height and weight, RFM factors in waist circumference, making it a more reliable indicator of body fat levels.
Knowing your RFM gives you a clearer picture of health risks related to excessive body fat, such as cardiovascular disease, diabetes, and metabolic conditions. It is particularly useful for individuals who are muscular, since BMI often overestimates their fat levels.
How to Calculate RFM
For Males:
[\text{RFM}_{\text{male}} = 64 - 20 \times \frac{\text{Height}}{\text{Waist}}]
For Females:
[\text{RFM}_{\text{female}} = 76 - 20 \times \frac{\text{Height}}{\text{Waist}}]
Where:
- Height is your height in inches or centimeters.
- Waist is your waist circumference in the same unit as height.
Since the formula uses the ratio of height to waist, the result is the same regardless of whether you use inches or centimeters.
Calculation Example
Male Example: Height is 70 inches and waist circumference is 34 inches.
[\text{RFM} = 64 - 20 \times \frac{70}{34}]
[\text{RFM} = 64 - 20 \times 2.06 = 64 - 41.18 \approx 22.82]
The RFM is approximately 22.82%.
Female Example: Height is 160 cm and waist circumference is 70 cm.
[\text{RFM} = 76 - 20 \times \frac{160}{70}]
[\text{RFM} = 76 - 20 \times 2.29 = 76 - 45.71 \approx 30.29]
The RFM is approximately 30.29%.