I believe that photograph is from 1999 when he got arrested. He was sentenced to death in 2000, so that's over 20 years waiting. And yes, obesity is becoming a problem inside prisons too (prisonlegalnews.org).
Not sure about death row, but many prisons have a commissary where you can buy junk food with personal funds either brought in with you from the outside or transferred from friends and family outside. Some people don't get fat -until- they go to prison.
This attempt had nothing to do with the failures of lethal injection. They tried to fill a room with 0% oxygen and it failed spectacularly causing suffering and trauma, but not death.
They failed specifically because they didn’t try to fill the room with nitrogen. The dude was insistent that a priest be allowed to stay in physical contact with him for the duration of his execution. So they couldn’t fill the entire room, because the priest was in the room with him.
Instead, they tried using a gas mask so only he would suffocate. The issue was that the mask failed (or wasn’t designed properly, or wasn’t used properly,) and oxygen was allowed to get into the mask for an extended period of time; His attempted execution lasted for way longer than it should have, because he was still able to get oxygen.