Any fast-food restaurants that actually use soy protein in their hamburgers, etc.?

We’ve all heard a joke, I’m sure, similar to such at one point in our lives:

Jon: …ah, here’s a (McDonald’s) burger left over. Want it, Jack?
Jack: Nah, I’m full. Care for it, Lisa?
Lisa: No thanks, I’m vegetarian.
Sue: Don’t worry; it’s not meat, it’s McDonalds…

and, a laugh was had by all.

It seems, however, that McDonald’s does use 100% pure beef in their patties. Therefore, I’m wondering if there are any fast food chains that indeed use something like soy protein to stretch the beef, all the while making no steadfast claims about their “hamburgers made with beef”?

My father, who used to work for Arby’s back in late 1960s or early 1970s, said that their roast beef was cut with “beans” of some sort, which may have been soy protein. I don’t know how true this was, but the texture of Arby’s roast beef is certainly different than any other roast beef I’ve had, including sandwich meat.

The fate of McDonalds’ McLean Deluxe has kept most similar products off the market:

The pizza restaurant I used to work for had “textured vegetable protein” in its hamburger. State or federal law required that our menus reflected this fact.

Hamburger never sold well as a pizza topping.

Harvey’s has quite a good veggie burger which has no beef. I have heard rumours they do this with their normal burger, but the website describes it as all beef. So prob’ly not.

In the press buzz for the BK Veggie (Burger King’s vegetarian burger) I remember reading that they didn’t want to use soy in it because an allergy to soy is pretty common in the population.

I don’t know about their hamburger patties, but one day I was at a Jack In The Box and they had just recently received a delivery. A carton of tacos (might have been just the meatish filling) was clearly labeled as beef and textured vegatable protein.