more info to edcuate the idiots
GSP has a HGH gut, TRT tits, Steroid shoulders and lats, etc.
If you look at GSP when he was starting out in the Canadian Fighting Championship, his physique was essentially the same as it is now. Shoulders, tits and gut included. Over a decade of fighting has aged him, he's no longer as cut and his shift from weightlifting to bodyweight fitness and gymnastics has changed his shape a bit, but he has not undergone any major physical change like most fighters on PEDs do at one point in their career (TRTVitor, Fitch, Bigg Rigg, Uberreem, Powerlifting Jones, etc.) or shown anything but a natural downward curve in his speed, cardio and endurance over the years.
Maybe he started early? When he was starting out, he lived in his parent's unfinished basement in what's essentially a backwater farming community. He spoke little to no English and he drove a rusted Pontiac Firebird every weekend to New York from his village to train BJJ and stayed in shitty youth hostels. He paid his BJJ tuition with rolls of change and worked part time as a garbage man and a club bouncer will studying full time at University. GSP was broke as fuck.
Up until his second fight in the UFC, GSP's fight career was a hobby according to most interviews he gave in the CFC and a bit later. He did Karate and dabbled in Jiu-jitsu, but he had yet to seriously study wrestling, join a real camp or make any kind of real money. At that point you have to ask yourself wwhy the hell would he spend what little money he has on designer PEDs instead of coaches, training, equipment or just plain gas and food at that point in his "career"? Occam's razor...
Then to now, GSP has aged a bit and has slowed down, but physically he's stayed virtually identical. Most of his recent wins have come through ringcraft, technical striking and smart ground work: all means that point to an experienced mind rather than an unnatural physique.