I don't blame her for gaining weight I think as a young adult age weight fluctuates more than when you're a teen! I just hate how she lies about it and is just nasty, she'd be much more relatable if she owned it and was honest.
And if she tried a bit more, cared about more than the colour of her walls, didn't change her mind every 5 mins- actually stick to what she says, there might be a lot to fix here.... but her weight I think should be the least of her problems her personality defiantly needs more attention and fixing!