I remember seeing parts of this story on Deviantart, it was about this one thin woman wanting to get fat but couldn’t for some reason, and a company manages to create something called adipose enhancers, which gave the story the name “Chubby Gummies”, but the company was lead by another woman who wanted money and made it so the adipose enhancers were addictive, making people keep taking them until they reached immobility, which our main protagonist becomes at the end. The ending had a sort of sad feeling to it and I believe there was a real life female celebrity in it too who also took the adipose enhancers and became immobile.