honest question, and please dont take this the wrong way.
but, WHY is weight gain a thing?

Some people just prefer fat, and so gain excessive weight really quickly is attractive to them. It's kind of like hyper or transformation in a way

Thank you. I only ask because my partner and i were both considered fat as kids and did hard work to lose the weight. So i couldn't understand the appeal, when being so big would cause severe health issue.

I appreciate your calm explanation

It really depends on a person by person basis. Some take to fat different, no people shouldnt be obese, but fat isnt bad. Fat isnt always unhealthy, neither is being extremely thin. Putting a generalization on any body type is unfair, because every person is different, what might be unhealthy for some might not be for others.
If you dont prefer it that's fine, but I would definitely not criticize anyone who does find it attractive, cause there are those who tend to be very thin and wish to be fatter. Everyone views their bodies differently. And no one should shame another for a body that they might not be able to control, including those who have bullied you in your past.
I too was bullied as a kid thanks to my body and I have actively tried to change my body to be thinner , but as time has gone on with no real change after changing my diet, exercise, etc I am just big and will probably stay big for the rest of my life. And sometimes that's just how life is, everyone's body is different and reacts different to things. So I hope this helps a bit to understand why and how some can find it being attractive

Again, just honestly asking, not bashing or shaming. Pure curiosity.
thank you for your time and detailed response.

I know you weren't, I was just explaining more in depth.

my main concern moreso is that EVERY TIME i go to search for anything in FA, whether it be Aggretsuko characters, or Final fantasy wallpaper, or cute creatures that i enjoyed as a child...... i end up finding a (pardon the expression) grossly overweight and debilitated fat version of them. I will admit, to an extent it makes me physically sick. (again not trying to be crass) but the concept of health at that size is nonexistent and concerning. While true many say that losing weight isnt easy, and they are correct, it is NOT IMPOSSIBLE. I have seen plenty of actual people go from 3-400lbs down to approx 210 and NOBODY will tell you that it was easy. It takes pure dedication and time. idk man it just irks me the wrong way to see people embracing fat.

youre adorable, ty!