You making personal decisions about your own body isn’t a bad thing.

However, it would be highly regrettable if you never took time to deeply reflect upon WHY it seems like every aspect of your life has improved, ergo never want to be fat again. The vast majority of those ‘improvements’ to your life are because you now receive more thin privilege than you did when you were heavier. By having a thin body, society now accommodates you differently; you now have rights, advantages, immunities, and benefits because you moved from the marginalized group (fat people) to the dominant group (thin people). You did not earn those ‘improvements;’ society confers this social status and associated benefits to the dominant group.

Clearly, you want to retain that social status and the advantages it affords. Who could blame you for not wanting to be abused, bullied, and systemically oppressed! You accomplished this by changing your body and conforming to the dominant group. Again— your decision, and you have full autonomy in decisions you make about your own body. But the point here is that no one should have to change their body in order to be treated with respect / as a human being / with equality. We should all have access to those rights, regardless of the size of our bodies. The size of our bodies alone has nothing to do with inherently “good” or inherently “bad.”

Additionally, taking your personal decisions and their outcomes —aka, anecdotal evidence— and using it as medium through which you’re shitty to other people is indisputably bad. What do I mean by shitty to other people? You looking down upon fat people because now you’re thin and better than = BAD. You applying your experience of your changing body size to others and their decisions about their bodies = BAD. “If I can do it, so can you!” = BAD. So I’m hoping you’re avoiding those pitfalls of gaining privilege and not propagating the marginalization of fat people.  

You know from personal experience the difference in your life —how you were treated by others, your access to those benefits— between when you were fat and when you were thin. It would be asinine and willfully ignorant to not see the glaring social injustice. THAT oversight would be BAD.