Who is this girl stuffing food in her face, and what show is it from? What show is this from?

 

what exactly is happening? 

I found in this amv but the source for it (this is from boom boom dollar within that amv, at 22:04) only says "various".
I think this is maybe from Kareshi Kanojo no Jijou.


  Yukino Miyazawa is a Japanese high school freshman who is the envy of classmates for her good grades and immaculate appearance. However, her "perfect" exterior is a façade, a charade she maintains to win praise. In the privacy of her own home, she is spoiled, stubborn, a slob, and studies relentlessly and obsessively to maintain her grades. On entering high school, she is knocked from her position at the top of the class by Soichiro Arima, a handsome young man whose very existence Yukino considers a threat to the praise on which she thrives, and she vows to destroy him.


 

Seems like this could be it.

Edit: I am absolutely sure this is it as I found another image from the series. The scene occurs during episode 11.