Through some very special soup, the young girl becomes older, heavier, and even picks up a cute Russian accent. Her morals also radically shift, and she goes from frigid to slutty-sex pot in no time. Her boyfriend couldn't be happier.
The story hits all my buttons. It's a great example of both weight gain and age progression being viewed from a positive lens, rather than just as a punishment. I'm also partial to stories with an Eastern European flair, as some of my own writing will attest. The story is told with a lively narrative and flows nicely.
The only (very minor) criticism I'd have is that the transformation sequence itself could be longer and more detailed, especially physically. I always prefer a lot of detail on the process and the gradients involved in a slow change. But the post-transformation descriptions are pretty vivid. So this is by no means a big issue.
Overall, I'd give this a recommend if you're looking for an age progression/weight gain story with an interesting personality change. And if you love the story, check out the author's blog.