Thinspo was originally "thin and sporty" (Thin+Spo) and promoted a super healthy and physically fit lifestyle and positive choices.
Over time it has been co-opted by those with deeply negative body image issues, and those with anorexia fetishes.
I've just heard people saying it as 'in-SPO-ration' for so long that a -spo suffix seems more intuitively to be a truncation of -spiration.
Thinspo was originally "thin and sporty" (Thin+Spo) and promoted a super healthy and physically fit lifestyle and positive choices.
Over time it has been co-opted by those with deeply negative body image issues, and those with anorexia fetishes.