McKinnie, 33, has dealt with weight issues throughout his 11-year career. When he signed a two-year, $7 million contract in May, McKinnie agreed to play at a lighter weight, even lower than last season's playing weight of 352 pounds.
"Bryant is just too heavy right now. He needs to lose weight," Harbaugh said. "My guess is he lost quite a bit today. He's in good shape and he's got good cardiovascular fitness. I can tell he's worked hard. But I wasn't real comfortable putting him out there today at that weight. We'll figure it out in the next 24 to 48 hours. When we figure out the best way to deal with it, he'll be out there."
McKinnie was held out of offseason camps last year because of his weight and he didn't start a game in 2012 until the postseason. In four playoff games, McKinnie allowed two sacks and only one other additional quarterback hit. The Ravens re-signed him this offseason, hoping his past weight and work ethic problems were in the past.
"I'm not sure who's more disappointed, Bryant or I," Harbaugh said. "We had a long talk about it yesterday. It wasn't that the effort wasn't put in. There's an issue, but we're going to get it fixed together and we're going to get him out there."