Almost half the calories in a Big Mac are bun. Non-sugar Carbs, via calories, are why we are fat.Chips, bread with everything, buns. Seriously, watch what's on your plate as you eat for several days.
Not according to these links:
Big Mac bun, 180 cal: http://caloriecount.about.com/calories-mcdonalds-sesame-seed-bun-i53842
Two all-beef patties, special sauce, lettuce, cheese, pickles, onions - on a sesame seed bun.
What the jingle doesn't tell you is that the Big Mac bun has 3 pieces to it, not just two like the regular bun. The middle section is basically the same as the bottom section in size.