I'm flying United from IAD, and would like to stop at Terminal B (near gate 71) to get my dinner, before my flight that departs from Terminal C. How much extra time would it take? I'm seeing that there's the train that takes you from post-security to B, which shouldn't take long, but then after I finish my dinner, I'd have to circle back all the way to C and walk that long walkway to the main C hall.

Realistically speaking, how much extra time should I factor in? Would going into B take me way out of my way, or is it really not too bad? I normally take DCA, but taking advantage of the Metro to go to IAD, so I'm pretty much an IAD newbie.

Thanks!