For example, Mister Donut makes various sugary pastries that sometimes resemble donuts. Their products have some fat and sugar in them, but they make up for it with an amazing, slightly crunchy, texture and many interesting flavors. Similarly, the hamburgers at McDonald's seem to be of somewhat better quality. I would imagine the fatty American version of the McDouble wouldn't be received warmly in Japan.
It's also possible that I'm just trying to justify all the crap I buy to eat between the wonderful, healthy, meals my host mother makes.