SANTA CLARA, Calif. -- As San Francisco 49ers quarterback Colin Kaepernick worked to recover from the shoulder, thumb, and knee injuries that ended his 2015 season with seven games to go, the weight and strength that he'd worked hard to accumulate began to fall off. Kaepernick got so thin that he didn't even want to know the extent of the weight loss.

“I never weighed myself when I was at my lightest because I didn’t want to know,” he said.

What Kaepernick did know was that he wasn't anywhere near his listed weight of 230 pounds. Kaepernick declined to get into specifics of what he weighed or how far off he was from that listed weight, but he did offer a comparison that could put it all into context.

Colin Kaepernick said he hit the weight room hard this offseason to regain the strength that he lost while he was injured in 2015. "Training, that's my specialty," the quarterback said. AP Photo/Marcio Jose Sanchez

"There was a lot of weight I needed to get back and a lot of mobility that I needed to keep while I did that," Kaepernick said. "So, my body feels good. I feel ready to go and once again, I’m excited.

"I don’t look like my high school self anymore. I feel like I look more like an adult now.”

Indeed, Kaepernick returned to 49ers training camp over the weekend looking more like his old self. To get back to a more comfortable weight, Kaepernick said he ate as much as he could for as long as he could. That part was apparently more difficult than the long, grueling workouts he put himself through in the weight room to make sure he was adding the right kind of weight.

“Training, that’s my specialty," Kaepernick said. "So, that’s not an issue. That’s not what I worry about. To me, I’m going out there focusing on competing, not worrying about cardio or anything like that.”

In addition to his health, Kaepernick also brought something else to camp that general manager Trent Baalke noted.

"He’s worked hard, he’s got his weight back, a smile on his face," Baalke said. "He’s ready to go to work and compete. That’s the most important thing for these guys is getting them in here, letting them work with the coaches, and go to work. We’ve got a lot to do."

For whatever tumult Kaepernick and the 49ers might have had in the offseason when trade rumors swirled around him, it appears that is a thing of the past as Kaepernick settles into coach Chip Kelly's offense. Kelly has made it clear that Kaepernick and Blaine Gabbert will compete for the starting job and so far the duo has split reps evenly in the first three practices.

Neither quarterback has exactly lit it up so far, though both have had their moments. Kaepernick offered a nice back shoulder throw down the middle during team drills this week but has mostly stuck to throws underneath, while Gabbert has been more willing to take deep shots. That could simply be a function of Gabbert's increased comfort in the scheme after practicing in it during the spring.

Now that he's healthy, Kaepernick is just getting his first opportunity to turn the mental reps of the spring into physical performance in front of Kelly and the coaching staff.

“Mentally, the one thing that impressed me was how sharp he was in staying on top of everything," Kelly said. "He was in every single meeting asking really, really intelligent questions. He seems like he picked things up fairly quickly. If you watched him, and anybody that was here in the spring time, he stood directly behind the quarterback, whoever was in, and took snaps and was getting mental reps and there was a lot of times where I probably had more interaction with Kap than I did with the other quarterbacks, because I’m back there talking to him. You know, ‘What’d you see? Where’d you go? It was Cover-2, I would have thrown it over there.’ He was getting the mental reps out of it. He’s back, from a physical standpoint, he’s been cleared. We’ll see where he is from that standpoint, but mentally he was really sharp in the spring and really impressed with him from that standpoint.”

One thing Kaepernick has shown in the early part of camp is that he still has the ability to run when things break down. Whether a designed run or a scramble, he's made some plays in team drills by breaking contain and picking up chunks of yards. That's something that Kelly's offense lends itself to and part of the reason why Kaepernick likes the scheme.

“Yeah, this offense gives, I think, the best opportunity to every offensive player to make plays," Kaepernick said. "I think the scheme is great and puts players in the position to go out and make plays and have big plays at that.”

In discussing the competition on Tuesday, Kelly made it clear there won't likely be a winner between Kaepernick and Gabbert any time soon. Kelly said Tuesday that preseason games will be "huge" in the process and it's safe to assume that how they perform in joint practices with the Denver Broncos and Houston Texans should also offer a little more insight.

"The one thing with Kap that you’re never worried about is his work ethic," Kelly said. "He’s kind of a workout warrior. It was just really getting him back to [full strength], he had a thumb [injury], he had a shoulder, he had a knee. Let’s get him back to 100 percent and let’s see what he can do.”