After noting that some of his weight gain was due to the so-called "freshman fifteen," Jackson added: "In my family we're genetically real tall and real big. I stopped growing taller, so I guess I'm widening out."
Tennessee's coaches hope he continues "widening out" for a few more months, at least. At 6-2 and 240 pounds, Jackson is still undersized for a Southeastern Conference defensive end. His size wasn't a problem last fall, when he redshirted as a linebacker prospect, but he's facing much bigger blockers now that he's playing on the line of scrimmage.
"I really think I need to put on a few more pounds before the season because of the difference in the size of the guys," he said. "It's a big difference from what I'm used to but sometimes my strength makes up for the size."
Even undersized, Jackson believes he has found a home at end. There are three principle reasons for this:
One, he played defensive end during his days at Demopolis (Ala.) High School.
Two, the position is similar to the outside linebacker position he played while redshirting last fall.
Three, his position coach this spring at end is the same guy who was his position coach last fall at linebacker.
"I'm really comfortable with it because it's the same coach I had at linebacker, Lance Thompson," Jackson said, adding that the rush end position in Tennessee's scheme is "basically the same" as the position he filled in high school and as a true freshman last fall.
"The coverages are the only difference," he added, "dropping into coverages and learning to key off the backs."
Despite putting on 35 pounds, Jackson says he has maintained the exceptional quickness he displayed at 205. He wore a weighted vest during the offseason to grow accustomed to carrying 240 pounds. So, now that he's carrying 240 pounds without the vest, the weight seems natural.
"Right now I'm at a comfortable weight," he said. "I've been working with my weight."
Although he's still undersized for an end, Jackson believes he's a good fit for the position.
"It suits me very well," he said. "I just have to pick up more weight. Playing against 300-pounders is a big difference."
Another big difference is learning to play in a three-point stance instead of the two-point stance he played in last fall.
"The toughest adjustment is basically putting my hand back in the ground," Jackson said. "The thing that's been holding me back from using all my skills to the fullest is putting my hand in the ground."
Still, he says he played from a three-point stance in high school and that "it's coming back to me."
Adjusting to 35 additional pounds and a change in positions is no small task but Jackson is optimistic. He believes he's making steady progress.
"The most progress is learning the plays," he said. "I'm learning them faster than I expected I would. Last year I had trouble learning the linebacker plays and coverages.
"As I get back (to end) it's more remembering how I played and the keys I used in high school. It's becoming simpler the more I get into my playbook."