"I was about 260 pounds last year," he said. "Now I'm up to 283 but I just got moved back to end, so now I have to get back down a little bit ... like 270 or something.
"I put on the weight," the 6-foot-2 junior added with a laugh, "and now it's got to come back off."
In addition to added heft, Walls says he has added considerable strength in recent months.
"I feel a lot stronger than last year," he said. "My bench (press) went completely up. It's up to 405 pounds after being 350-something last year. And my squat is up to 515 after being about 405 last year. So, my strength is shooting up."
Although he weighs nearly 60 pounds more than he did in high school, Walls says he feels as mobile as ever.
"I'm still quick with my feet," he said, "so I've got to use that quickness to beat the guards and tackles. Now I've got the strength to go along with quickness, so that's a great thing."
Although he was a heralded 225-pound defensive end at Olive Branch (Miss.) High School, Walls was projected to be a linebacker in college. After boosting his grades and his bulk during a year at Hargrave Military Academy, however, he saw backup action at defensive tackle for the 2009 Vols. Now he's returning to the position he played in high school.
Despite bouncing from position to position, Walls' easy-going nature has never wavered. He is the epitome of the word "unflappable." That was evident last August, when he was running first-team at tackle until he sustained a season-ending Achilles tear a week into fall camp.
Now fully healed, he is excited and eager to resume his career.
"I feel 100 percent," he said. "The trainers did a great job of getting me back out here on the field."
Walls even managed to find a silver lining while missing the entire 2010 season.
"I feel like I know the game a little better because I got to sit back and watch," he said. "Things are coming a little easier because I feel like the game is slowing down a little bit for me."
Watching Vol defensive tackles from the sidelines last fall, Walls says he noted mistakes he had been making when he was filling that position.
"I saw where I was supposed to be and when I was supposed to be there," he said. "I learned the importance of reacting quicker, and I learned that by watching."
Although he has never played end at the collegiate level, Walls believes he's adjusting quickly.
"It's just a matter of getting back familiar with the alignments and reads that I was taught in high school," he said. "Coach (Lance) Thompson is doing a great job of transitioning me back to end."