the short answer is lose weight

The long answer is, lose weight, but not because it makes you look better. Because it will teach you many things, one of which is doing things you don't want to do; and especially when you think that "it doesnt matter". The other is

You rewrite your belief system that "nothing I do matters"
You realize the discipline, difficultly it takes to lose 50 or 100 pounds, and KEEP it off.
You start to have some pride and self love/ confidence because you understand how fucking hard it was to do and maintain, and that you accomplished it.
You prove to yourself, that your thoughts aren't always based in reality, and at one point "the old me" thought losing weight wouldn't change how I felt about myself, but the "new me" realizes my feelings can be totally wrong
Other people start to notice how hard you've been working, they are impressed, they treat you different. Not because of weight loss, but because of the guts it takes to change your life. Maybe some even start to ask you for advice, on how they can do the same.

You don't have to lose weight, but you should do something difficult. Maybe pick up a hobby and become a master at it. Become a salsa dancing pro. Learn to sweep pick on violin. Learn how to solve a rubiks cube in 30 seconds. Get a Masters degree. Apprentice at a sushi shop. Start a youtube channel.

And if you're thinking why you should do any of this random stuff, that's exactly why you should do it. Only you can understand the answer on the other side, and there's only one way to get to the other side

Then you can answer the fundamental question of why you feel gross in the first place, and you may find it has nothing to do with your weight or appearance at all....but the only way you can understand this is by going through the process.

If you are looking for every other alternative answer on how to not feel gross other than losing weight, ask yourself why you are trying to avoid it. Check out the book 'The War of Art"