Peacock, who underwent arthroscopic surgery Oct. 6 to repair a torn labrum and remove bone spurs in his right hip, dropped 28 pounds in the offseason and is noticeably slimmer as camp begins.
"I hit the gym pretty hard," he said. "I worked hard and [I'm] glad to see it paid off. Hopefully, [losing weight] doesn't hurt my fastball, though."
Peacock is scheduled to get on the mound Sunday and throw a bullpen for the first time since the surgery, but he's behind the other pitchers in his preparation for the season. Although the one thing that matters to Peacock at this point is that he feels "awesome."
"My legs feel awesome, and I can actually move it around with no pain at all," he said. "I haven't had back problems all offseason. I'm pretty excited."
Peacock started last season in the bullpen before making 24 starts in the rotation, setting career highs in appearances (28), starts (24), innings pitched (131 2/3) and strikeouts (119). He went 4-9 with a 4.72 ERA.
Peacock, who tenuously held down the No. 5 spot in the pitching rotation late in the year, dealt with back problems in September, which could have been a result of his hip injury.
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.