#DailyBloggingChallenge (247/250)
"Defining one's jawline" assumes from the get go that one is slim enough to see the changes in one's face.
This is one of the main issues on muscle defined regions pop, the other is having large enough muscles to show their definition.
Thus muscles that lack much fat deposits close by are much easier to see change compare to others that don't have this luxury.
#DailyBloggingChallenge (248/250)
When looking at one of the more popular regions, the abs, this could almost be the most typical examples.
On top of the muscle definition and fat deposits, another argument made is genetic make up as in the excuse of not getting the preferred natural (non-surgical) result.