I think not from drugs you may used to drink much cola alchole or eaten too gassy things ? That low doses cant add that size you are talking about in very short time.. I think you gotten belly fat from other issiues. Maybe you can try 250mg test 200 deca ? IF you are senstive. Also it will be cheaper..
Canberk i know you have more experience than me, but if he wants to get results, he can achieve them just by pushing his body into puberty levels.
300 TestE will do the trick but he will miss the DHT, since i don't think he can get easy Stanolone, the only thing he can do is stacking 2 similar DHTS, Masteron and Proviron can do the job. Then he will need also to trick thyroid, hgh and igf-1 but it will be even more expensive.
I would run this year long: 300 TestE 300 MastE 350 Proviron(skip that if costs too much) ew + 2 IU hgh Pharma grade 7/7.
If you have hair loss issues etc etc, DHTs sides in general, Masteron and all DHTs aren't a good thing to keep in.
Add some Deca at low dose for joints relief 150-200 Deca and a little anabolic kick.