I once heard its possible to live off beer. Like, just drink beer, lets say 8 per day is roughly 2000 calories, eat a pill for all vitamins and that's it. Probably wont even get drunk if you spread them out. Only thing you'd be missing is protein and fat. Maybe eat a fish once a month.
Eating lots of veggies won't though, if you do it right. Deep fried potatoes at every meal, that kinda thing, bad time. Kale salads with chili-fried tofu, doing fine.
Unless they have gelatin! I was still finding believed snacks that I had no idea used gelatin for years. I gotta find me some mallowcreme pumpkins I can eat