NBA star LeBron James is using the off-season to get in serious shape. The basketball player recently spoke to Sports Illustrated about his weight loss regime and revealed that his key to fitness is all about self-control.

And the disciplined athlete is also looking to his footwear to push his improve his workouts.

"I had no sugars, no dairy, I had no carbs," James told the magazine when discussing his weight loss plan. "All I ate was meat, fish, veggies and fruit. That's it. For 67 straight days."

While the four-time MVP described his diet as "very strict," he admitted that the meal plan was a "mental challenge."   

James avoided telling the interviewer how many pounds he actually lost in that period, but he did reveal that after his significant weight loss, he planned to pack a few more on before the start of the season.

The star, who recently moved back to the Cleveland Cavaliers, is now promoting his new project with Nike, a sneaker called the "LeBron 12," which was unveiled on Tuesday.   

"[It was a priority] for me to be able to have a shoe that allows me to be fast, not weigh me down," explained James in the interview. "The new technology is lightweight. It allows me to explode. When I land, it allows me to absorb the landings. It's great." 

As for Nike, James couldn't be happier with decision to team up again with the sportswear brand.

"That's the great part about my partnership with Nike. ... [If something isn't right], we're going to continue to go back to the lab to figure it out," explained James. "I was able to wear the shoe some games, some games I wore the 'Soldier' shoe. [The issues with the LeBron 11] hurt both of us. We loved the shoe so much, the 11, but it wasn't performing how we wanted, the way that Nike and myself are capable of performing. We started to get on this [12 model] right away. ... It's given me great responses."