Actually, yeah, you’re right! You are harsh. Here’s why.

The girl who is “dumb and hungry” may be suffering from a condition known as body dysmorphia. It doesn’t seem like you understand this affliction, so allow me to break it down for you: 

Body dysmorphia is a mental illness that causes individuals to hone in on their perceived flaws. In perfect shape and health, someone suffering from this disease will still see themselves as not thin enough. The evil thing about body dysmorphia is that it never allows you the peace of mind knowing that you are enough-- every waking moment, it tells you that you are not. Thinner, thinner, thinner. And then you are, but it persists: thinner, thinner, thinner. 

But wait, your ignorance prolongs into another dimension! So let me explain this other reality to you. This illness can facilitate a cycle of rumination: the relentless act self-imposed harassment. If we believe anything, it is ourselves, so imagine continually facing the pain of overbearing imperfection. In time, this cycle can manifest itself in an eating disorder, like anorexia nervosa. Which, let me assure you, is no laughing matter. And it is not a choice, it is a symptom. A symptom of a mental illness, something it seems that you aren’t able to grasp. 

I can assure you that said individual doesn’t refrain from eating at lunch because s/he thinks it is “cute.” So stop the stigma. Try to learn something factual. And please, for the wellbeing of everyone around you, get over yourself.