Yeah I think Riddick Bowe would have still grown to be an abnormally large man anyhow.

In fact there is some evidence that caloric restrictions can lead to a taller+leaner body type than the shorter+thicker type that high calorie diets lead to.

The ancient Spartans were first to employ such a diet to their soldiers in the hopes of producing taller more athletic soldiers.

Of course I think diet has mcuh to do with the overall size but I have a feeling Riddick was gonna be around 6'5" tall anyway!! Just maybe not so hefty!! Or chubby.