Lions' Michael Williams out with injury

ALLEN PARK, Mich. -- Michael Williams has another setback.

Williams, who is in the process of adding weight as he transitions from tight end to offensive tackle for the Detroit Lions, has an undisclosed injury, one serious enough for him to miss Thursday's practice.

"Not a long-term thing," Lions coach Jim Caldwell said. "A few days, maybe."

Williams declined to discuss the injury but said missing any time does hurt him.

"It's a setback just from getting reps on the field, which is the most important thing," Williams said. "But I'm still here learning. I feel like I'm more of a student of the game when I'm out, when I'm hurt, so I have to focus more because that's all the time that I have then."

Williams said he gained 15 pounds -- up to 298 pounds -- as he attempts to make the switch. His goal for the 2014 season is between 305 and 310 pounds. At that weight, he then needs to see if his speed remains somewhat similar.

What did he eat to put on all that weight?

"We in Alabama at the time, so it's just whatever you kill, that's what you eat," Williams said. "Nah, it's a joke, man. It was just good, home-cooked food."

Williams was one of four players to miss practice Thursday. Defensive end Ezekiel Ansah and wide receiver TJ Jones remain on the active physically unable to perform list, and offensive lineman Alex Bullard also sat out.

The Lions also made a move Thursday, releasing receiver Cody Wilson and singing defensive end Kris Redding out of Wake Forest.