Michael Pollan, in his book, "Food Rules," exhorts us to eat food that our grandparents (or great-grandparents, depending on our age) would be able to recognize as food. No Gatorade! No roll-up fruit! No foodstuffs in squeezable tubes!
Alas, do you think Pollan had squirrels in New York City's Central Park in mind when he issued his maxim? I caught this guy licking a chocolate snack cake wrapper bone dry yesterday; I have a feeling his paternal grandmother would prefer he ate an acorn.
By the way, studies have shown the addictive nature of the fake sugars, salts and fats so prevalent in processed foodstuffs. I'd bet that the same response can occur in animals.