McGugan has struggled with injury problems this season
Nottingham Forest manager Billy Davies said he left midfielder Lewis McGugan on the bench for the 5-0 defeat at Burnley because of "indiscipline".
Davies said last week he thought McGugan, 20, was overweight and unfit.
The Scot told BBC Radio Nottingham: "I've had to drop Lewis because of off-the-field indiscipline.
"I'm not going to go into it and it's not just Lewis, there are a couple of players we must demand more of regarding their lifestyle."
Forest's dismal display at Turf Moor has left them perilously close to the Championship's relegation zone.
We owe the fans a massive apology because that was a disgraceful display
Billy Davies
Davies, who took over as boss in December, said some of the Reds players are badly letting the club down at present.
"This is something we have to sort out," he added. "It's about eating habits, preparation for games, everything.
"Unfortunately, there are one or two who have to be with the squad at the moment because of our situation but we'd like to send them away to let them understand what's required.
"Long-term, there will be questions asked with regards to the type of players we need here because the fans deserve better."
Davies admitted Forest owed their travelling supporters a "massive apology" for Saturday's performance.
"We owe it to them, because that was a disgraceful display," he said.
"It was a poor first goal to concede, a terrible reaction to conceding and we offered nothing. We've got players at this club who are costing us clear.
"These players are very well paid and we owe the paying public a lot more than we are giving them."
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