the people that got fat probably got more muscle, too, they just overate and were lazy on top of it.
To quote Lyle: "No shock, the placebo group had no change in anything. Training alone got the guys four and a half pounds LBM in 10 weeks. But steroids alone worked better: 6.6 pounds LBM in the same 10 weeks. With just one shot in the butt every week. Clearly training and exercise was synergistic and the third group gained close to what you’d predict from adding steroids and training alone together. But steroids alone built more muscle than training alone and just as much strength."
training alone for 10 weeks: 4.5 pounds LBM gained
600mg of test per week and no training for 10 weeks: 6.6 pounds of LBM gained
600mg of test per week and training for 10 weeks: 13 pounds of LBM gained
point is, roids make your muscles grow.
EDIT: maybe i don't know what you mean by "just worked out" effect.