Question

is this right: la comida que son insalubre I want to say that "unhealthy foods" or "foods that are unhealthy"

Answer 1

"Comida insalubre" is all we have to say. It means "unhealthy food."

Answer 2

The best way to put it is:
plural:: "Las comidas que son no saludables" / The foods that are unhealthy
singular: "La comida que es no saludable" / The food that is not healthy

Answer 3

I think "comida insalubre" would work out just fine. An alternative could also be "La comida poco saludable" or "La comida malsana".