tbh what I want deep down is this.
The reason im fat is because I havent been expressing my true self properley. The only reason in the world I would dye my hair brown as opposed to the attached pic is the reaction from society.
If being "fat" is what makes you unhappy, and if you are "fat" because you don't express you self the way you want to be, the solution seems simple.
Go for it. No matter what you do, what you wear and who you talk to, there will be people judging on it, and there will be people judgemental. There will be people making up gossipy stories, and others will make new stories. It will happen, no matter what you do. If you make yourself unhappy by trying to prevent that, you only make it worse.
Be who you are, unless it goes against ethics or is highly impractical. Would the way you look make you lose your job or so, you might need to compromise, for the rest there is no need to do that.