That is because in Norwegian present and present continuous is pretty much the same. Norwegian does not have a "ing" form to specify what's happening right now. So "Hun spiser kjøtt" can mean both that she eats meat and that she is eating meat.
You always have to put "ikke" after the verb. Don't worry though, saying things like "hun ikke spiser kjøtt" is a very common mistake especially for British and American immigrants in Norway. You'll get the hang of it eventually. :-)
"She's eating no meat" is incorrect, yet "She eats no meat" is correct... are you kidding me? So far we've learned that Norwegians doesn't tell the difference between continuous and simple, but here it does matter.