Everyone is different. "Gyne" can be glandular or "psuedo" - i.e. fat - and any mix of the two. Working out can improve the pseudo, but won't touch the glandular. If you have any degree of "real" gyne it can be emphasised by reducing bodyfat, in that it will sit on top of your increased muscle mass.
It really does depend on the individual. Many people find that the gyne is so obvious when "buffed" that letting the bodyfat disguise the gyne is preferable - they'd rather be seen as just another chubby than some weirdo intersex freak. No offense meant here - I was in that position and thats exactly how I felt.
But I did build up a fair amount of muscle, and for the most part when clothed people would just seem me as a big dude. Having clocked the muscles they certainly might be less inclined to say "hey, you've got boobs" - so on that basis some serious gym work can help you get by! But when the chips are down and the shirt comes off, there ain't no place left to hide.
And here's the real pisser if you've spent hard gym time building muscle naturally ('cos we know where 'roids take you and don't want to get any more of that thanx!) ... as soon as people spot the gyne they assume you're juiced and that's why you have the gyne. Any kudos and respect you had as a hard training gym rat out of the window.
OK, so back to the original post. there are some misconceptions there. Fat won't convert to muscle; if you're lucky and it hasn't been there long it can turn to energy, but thats it. (The inverse is also true, muscle can't turn to fat, as many suggest.) Gland and fat sit on top of muscles (you also have fat through the muscle - think marbled steak - and behind too, but mostly on top); the gland is generally surrounded by, and sat into, the fat. This is why simple glandular incision will leave a crater - the surrounding fat remains, with a hole where the gland was. This is also why "real" gyne looks worse when bodyfat reduces - the fat it's embedded in melts away leaving more of the gland visible. Lipo can help with that, and some surgeons might also redistribute the fat rather than just remove it.
Think of the gland as an iceberg, and bodyfat as the ocean. Most of the iceberg is under sea level, and not normally visible. Drain the ocean (come on, work with me!) and the iceberg will sit on the dry seabed - and look a hell of a lot bigger. Until it melts of course, but that won't happen with the gyne unfortunately!
So ... bottom line, working out gets you healthier, so go for it. If fat loss is your aim working the chest will not cause localised fat loss. Fat will go from wherever it was last deposited first generally, and from where it was first deposited last (the stubborn bits!).
If your gyne is mostly "pseudo", i.e. you're just a bit chubby, then this could be all that you need to get the bod of your dreams. Just be aware that generally where there is real gyne its likely that the fat there will be the last to go as it was probably the first to be deposited - gland tends to attract fat deposits as it develops.
But if, as you melt that fat away, your gyne starts to look more obvious then you know you have the real deal, full on glandular gyne, and you have three choices:
* Get chubby again to hide it
* Embrace it and to f**k with what anyone thinks or says
* Get it removed.
Just be aware that once you get there you can train like a demon possessed but it won't change the gyne - that is NOT a fourth option. Ever seen a pro bodybuilder ripped to competition condition with 'roid induced gyne? Think they could have trained and dieted a bit harder, the pussies? No, me neither. Yet despite this I listened to the counsel of ignorance and went down that route for a decade.
Before anyone starts (rob) - I AM NOT RECOMMENDING ANYTHING! Just laying out the facts for you to make up your own mind. Information is power. You'll never know how much I wish someone had given me this information when I was younger. I really, sincerely, hope that this will help someone.
Good luck, and be happy.