Is it normal men called my friend fat in the comments of a youtube video??

So, my friend happened to be in a youtube prank video. She's actually about 15 pounds thinner than me and I'm a healthy weight. When I went to look at the comments, I was shocked. Most of the comments pertaining to her were insults calling her chubby, tubby, fatty, chunky, etc. My friend is only 119 pounds at 5'4 so this disturbs me. If they think my friend who is a size small is fat, what do they think of a girl who is a size medium? Do men really see us as whales unless we're anorexic looking? In one of the comments, someone wrote "She's actually not fat at all" and then someone else replied with, "you can like whales, we don't care".

The only thing I can think of which I don't see how it's truly possible is that they really didn't look at her the right way. She was wearing a baggy tshirt that was really short along with yoga pants. I don't see her as fat in the video no matter how I look at it. Another thing is how some were calling her ugly when you can't see her face in the video as it's far away but my friend is way prettier than me and gets hit on all the time.

Why do people on youtube get so nasty/is it normal to call a girl that is 119 pounds at 5'4 fat? Should I lose weight because I'm bigger than her at 135? If this is really true, I guess men do prefer women underweight at 100 or less pounds.