Waist-to-weight ratio vs. body max index

The optimal waist / weight ratio (WWR) theory (1) is one of the most compatible with evidence regarding the lowest mortality body mass index (BMI).

But why do we need the WWR when we already have the BMI? This was a question that a reader asked me in connection with a post on the John Stone transformation (2).

The montage below shows photos of the John Stone transformation with the respective WWR and BMI measures.



Well, which one is the most useful measure, WWR or BMI?