I don't think he meant that GSP cut 15lbs the day of the weigh-ins. I believe he meant that he was fighting 15lbs heavier than what he weighed in at. It's not uncommon for a lot of fighters to "dry up" going into the weigh-in, and then come in for the actualy fight 10 to 15lbs heavier than the day before. Anyone cutting 15lbs in one day isn't going to have much energy or strength to walk around much less fight in a championship bought (unless you are grossly overweight).
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