ofcourse its possible,,you got many ways
1. post competition ..many guys add 20-30lb in 4-5 days,,no hormones needed usually but you add some dianabol there and you can touch 50lb in first week post competition
2. any human can add 15lb which is about 6-7 kg in 12-15 dys by using dianabol at 30-50mg per day,,it will be good size too ,,water but you will look swole and swole in gym rat terms = good ,,in any terms it = good if youre solid bodybuilder
3. eat everything around you and you will add 3-5 lg in 15 days,,ofcourse it will be fat ,,ofcourse you need to be in yruo teen age years maybe very early 20s for it to work ,,but it will be only fat,,you can gain 3-5 kg in 15-30 days this way,,it will look horrible though