How does one overcome the 'social stigma' aspect

[Blunderbusty]

Not knowing your particular situation, I hope you will forgive me for generalizing, but the stigma will be less-bad than you are imagining. By way of example, my wife has put on almost 100 pounds in the years we have been together. There are times when it is difficult for her: the occasional breakdown because she’s outgrown all her clothes, or maybe a lecture from the doctor will rattle her. Apart from that, the people who loved her don’t love her less for being fat. If they did though, I’m sure she would not be super interested in maintaining a relationship with such shallow people. Being in a loving, long-term relationship helped too, as friends and family worried less about her being “too fat to find someone”. The one time an ex-boyfriend did give her grief about getting fat, she pinned it (fairly) on me, and that was the end of it.

Sometimes I read stories about people facing discrimination at work for their weight. The “fat=lazy” prejudice remains popular, even when half the population is overweight. You may need to consider any potential weight gain in light of your current job and future goals, but this at least hasn’t been an issue with my wife’s bosses. 

If getting fat is something you want to experience for yourself (i.e. it’s your own wish and not your partner’s), you should go for it. As you have already demonstrated, weight can be lost if it turns out to be too much to handle. Good luck!