Loss of interest in lifting and bodybuilding, loss of motivation, joint pain, injuries, colds, sore throats, plateaus, loss of strength, loss of muscle mass.
The reason I was overtraining is because I was lifting heavy, which is good, but I was doing it too long, too often, without enough rest between workouts. Eating more and sleeping more did not help since testosterone plays a major role in recovery and I don't do steroids. All of these symptoms stopped when I stopped training the same muscle group more than once per week, cut my workout time down to 45 minutes or less, started taking one week off every 8 to 10 weeks of training. I'm still lifting just as heavy, eating and sleeping just as much.