는다면서

'You said you… so why…?'

-는다면서 quotes a claim back at the person who made it, and the point is the contradiction that follows: 안 먹는다면서 왜 이렇게 많이 먹어요? 'you said you don't eat — why are you eating so much?' Add 요 and it becomes a polite check on something you heard: 나이프랑 포크로만 다 먹는다면서요? 'I hear you eat everything with a knife and fork?' The shorter -는다며 means the same thing.

Register: casual; 면서요 is polite