<P> Mixed martial arts weight classes are weight classes that pertain to the sport of mixed martial arts . </P> <P> Prior to state sanctioning, weight classes were not mandatory since the competitions were held without the approval of the athletic commissions . For instance, the Ultimate Fighting Championship introduced two weight classes at UFC 12: heavyweight, which grouped competitors above 200 lb (91 kg), and lightweight, which grouped competitors under 200 lb . </P> <P> Weight divisions underwent many changes in the ensuing years, but the ability of promotions to autonomously decide their own weight classes eventually disappeared after athletic commissions began supervising mixed martial arts . </P>

When were weight classes introduced to the ufc