CHARLOTTE — The Panthers already see some juice from rookie defensive tackle Marquan McCall.

But there was a lot of juice he had to take out of his life before he could show them anything.

The rookie nose tackle made his NFL regular season debut last week at New York and impressed his coaches and teammates in a short amount of time with his quicker-than-you'd-think first step, and ability to anchor against the run.

Having ballast is helpful, and at 6-foot-3 and 345 pounds, he's still huge. But you can't just be large. You have to be able to move, too.

"He's wide. He's stout. It's hard to get under him; it's definitely hard to move him," defensive end Brian Burns said. "That's a prototypical nose body. He can create a lot of disruption in the middle for us, soon.

"One thing about him, he brings a lot of energy on the field, especially when he makes a play; he brings the defense up with him."

There were a few moments against the Giants, but McCall has shown throughout training camp he can make a difference. He had a fourth-down stop in New England and a sack in the preseason finale against the Bills, which showed he's more than just some large object that gets in the way of things. Burns said he likes the way he studies and accepts the coaching he's getting too.

Panthers head coach Matt Rhule said he was impressed with the early returns on the undrafted rookie and also with the way McCall has kept himself in shape. With the Saints coming in this week with a dynamic run game of their own, having that kind of player step up will be huge (no pun intended) after Bravvion Roy went on injured reserve.

"McCall got in the last game, and to me, played the run," Rhule said. "When you play the Saints, the first thing you have to talk about is the run game, their outside zone run game with Alvin Kamara and Mark Ingram, I mean, they have one of the best centers in the game in (Erik) McCoy, he can reach the nose like that. Guys like McCall, they have to be up and ready to go and ready to play at a really high level.

"I was really pleased with the way McCall played last week. He's a guy to me, that coming out in the draft at 365, now in the low 340s, he's done a great job here getting his weight down. I think he's going to be a really good player for us."

McCall grinned when asked about the weight, because he knows changing his body was the key to making an NFL roster.

He was a productive player at Kentucky, but going into his senior year, he made a deliberate effort to get from the other side of 380 pounds to something more functional and had 3.5 tackles for loss in addition to playing solidly inside.

One of the first steps was giving up the apple juice he loved from the time he was a kid, replacing it with water, and being more diligent about his eating habits as the day went on.

"I was a big juice fan. A lot of apple juice in my day. I cut out a lot of the juice, all the juice actually," he said. "I just had to teach myself, I can't eat in those hungry hours of 8, 9, 10 o'clock at night. It's about keeping my focus.

"Knowing there was a job on the line, I knew I couldn't mess that up. At the end of the day, I knew it was a job, so all that went out the window. So I didn't really focus on that. I was just trying to get my weight down as fast as I could and get as healthy as I could."

There have been wide-bodied nose tackles in the NFL before that could push 400 pounds and still be functional run-stoppers, but McCall can tell the difference in his game now.

"The 380-pound Marquan, he could move, but he couldn't move as fast as the Marquan now," McCall said. "So a 40-pound difference makes a big difference. Just dropping weight and getting in shape. I wouldn't be able to be in this type of shape if I was 380, for sure."

Make no mistake; he's still very large. But he's not so large that he's not able to help in other areas. With starters Derrick Brown and Matt Ioannidis able to play a lot of snaps, McCall will mostly be asked to play on first and second downs as the games go on, but he's shown some signs that he can be the kind of impactful player they called "Bully" at Kentucky.

He credits his old high school friend Patrick Riley for giving him the nickname during his freshman year for the Wildcats, and likes the way it fits.

"We were sitting at lunch one day, and he said, 'You should change your name to 'Bully Ball McCall,'' and I was like, 'Hey wait, that actually sounds good.' Ever since then, it's been Bully Ball McCall, so shout out to Pat.

"I'm bringing a lot of nastiness, a lot of toughness, a lot of power, and a lot of anchor in there in the run game. And I've always been the energy guy. I love the energy; I love to make guys excited and ready to go and have fun."

He had plenty last week. He admitted it was a "dream come true" being active for his first game, being in uniform for the national anthem and seeing the giant flag on the field, and all the stuff that goes along with playing in the NFL.

But then he went in and made some plays, and people noticed.

Having someone like Burns — a guy who can also make plays in a hurry that get people fired up — mention that you brought a tangible energy says something too.

"McCall has a lot of potential," Burns said. "I feel like once we get him going and get his confidence and he gets some experience, he's going to be really good."