"Super size me" is a separate idea altogether. That suggests overeating not a particular type of food. Obviously overeating is going to lead to some kind of problem no matter what you eat.
Further into the article they introduce a third component of the liver damaging diet. Sugar. Not everything on any fast food restaurant's menu has a lot of sugar in it. In fact it is the soda pop they sell which has the lion's share. IMO the sugar is worse than either saturated fat and/or overeating. Get all three, saturated fat, sugar saturated soft drink and more than you need to eat and you have a liver toxic formula. But even then only if you eat that regularly.
Eliminate just the soft drink (which contains other undesirable compounds like citric acid, caffeine, phosphoric acid and CO2) and you have reduced the potential for damage a lot. Eat a reasonable amount and the negative effect is rather small. Especially since most food chains have voluntarily removed trans-fats from their ingredients.
When people point to a Big Mac or a Whopper and call that junk food you have to ask yourself why. It's beef, wheat, lettuce, cheese, pickle, tomato, onion and mustard. Sounds like the food pyramid to me in just about the proper amounts of each.
I don’t eat that stuff. Sugar, I need to avoid but still can’t. I used to say that about sub sandwiches when my mother would tell me they weren’t healthy. I would say they have all the food groups.
The high fructose corn syrup is probably the worst part of the whole "value meal". I would like to see another "Supersize Me" experiment where he switched to diet soda. I bet the damage would be minimal.