Tracking waist size and waist to height ratio (WHtR)

Due to recent developments in research and analysis, it appears that the waist to height ratio will become the standard for measuring cardiovascular risk, as opposed to the BMI.  In fact, the study states that simple waist circumference is a better predictor of cardiovascular disease risk than is BMI.

http://jcem.endojournals.org/content/95/4/177 7.full

I know how to measure and compute my ratio, but I think it would be useful to consider modifying the application to track waist size, and showing a continuum of healthy ratio versus the person's current waist/height ratio.