People that have used to be fat, and then lost a lot of weight, will know how brutally different people will treat you. Whereas you'd practically be a ghost before weight loss, random people will suddenly look you in your eyes, smile, even start conversations with you.

Some will of course argue that you losing weight will also make you more confident, and thus you become more approachable. I think there's a lot of bias against fat people, against "unattractive" people, etc.

This also shows in the classroom, work, etc.

Of course, actually being conventionally attractive will come with its own perks. People will go out of their way to help you, and to support you. Over time this could very well boost your ego to also become more confident and decisive.

Having been overweight my entire life until recently, this is accurate. The "it's just your newfound confidence" argument misses the mark completely.

The baseline level of basic respect you receive from strangers such as simply making eye contact, holding doors, or initiating small talk changes almost overnight. It is a very bitter reality to wake up to when you realize you were basically invisible before.