On Tuesday, Jenna Laine of ESPN.com provided comments from Spence, who said he's focused on adding "a lot of carbs" to increase weight and maintain energy.
"Today was the heaviest I've ever been and I felt great. I was 263 today," he said. "I kind of just started playing with it [in the offseason] to see what works. I felt like if I just don't stop eating or drinking, I won't lose weight."
The Bucs will hope the transformation leads to a breakout season from the 24-year-old lineman, who's struggled to find consistency since they selected him in the second round of the 2016 NFL draft.
Spence tallied 22 combined tackles, 5.5 sacks and three forced fumbles in 16 games during his rookie campaign. A shoulder injury limited him to six appearances last year, and he recorded just nine tackles and one sack in those outings.
"Two shoulder surgeries—he's worked very hard to come back from that and he's lived in the training room and the weight room," head coach Dirk Koetter told Laine. "I think he's got the same motor and the same speed that he always had. We're anxious to see him get out there and do it in real football."
Spence is the team's chief reserve at defensive end behind starters Jason Pierre-Paul and Vinny Curry. A strong preseason could earn him more snaps once the regular season opens Sept. 9 when the Bucs travel to face the New Orleans Saints at the Mercedes-Benz Superdome.