I agree with this suggestion. But I would like to be rather more specific. There are a couple of measures that are of particular merit, imo. One is the ratio of 'abdomen to hip'. At least one study found this ratio to be an excellent proxy for CVD risk. Abdomen defined as circumference at navel level. Hip defined as the largest circumference below the navel. My suggestion is that both these numbers be collected, but just the ratio of them plotted.

Even more important, imo, for people practising CRON is body fat percentage. Probably the least unreliable easy way to calculate this is the US Navy method. I am sure you are familiar with this. My suggestion is that the required measurements be collected (for males that is height, along with neck and abdomen circumferences) and the derived number for body fat be the one plotted. Hope this helps a bit.