When studying disease traits it is always preferable to understand all elements of the etiological pathway.
A recent paper in PLoS Biology titled "It's Not How Fat You Are, It's What You Do with It That Counts" describes the "Adipose Expandability Hypothesis" as a way of explaining why some individuals develop metabolic syndrome and why others don't, regardless of how obese they are. What matters is your ability to store fat. If you're good at it you can stave off further health complications. If you're not good at it, you start storing fat in organ tissue, leading to further health complications even if you have no excess body fat.