A reasonably well prepared hamburger is not "junk food."

Think about it. Ground round (granted McDonald's mixes it half-and-half with wet cardboard), bread in the form of a bun, and the usual fixin's like lettuce, tomato, a little mayo (ingredients often found in salads), perhaps a bit of mustard and/or ketchup, and a pickle slice or two. Not junk food.

Most nutritionists I know of who remain current say that red meat should be avoided. No more than 1 serving (4 ounces) per week. The protein you get from meat should come from leaner sources - primarily fish or shellfish, then fowl.
White bread, which includes all fast food hamburger buns I've seen, is also frowned upon. Grain should come from whole grains, or at the very least whole grain bread. Processed flour has most of the nutritional value stripped from it.
Mayo, mustard, and ketchup frequently are overly sugared.
Pickles are exceedingly high in sodium.
Too much fat, sugar, and salt. High calorie, low nutritional value. How is this not junk food?