I had a similar experience with someone commenting on how healthy my lunch looked (chicken breast and a salad) when I was attending a lecture during which a buffet lunch was provided and asked me if I was following any specific diet. When I told her I was low carbing she went off on this huge lecture about how unhealthy it was until I pointed out to her how she had just been praising how healthy my lunch looked.
When she responded, "Oh, but you don't always eat like that, do you?", my reply was "No...usually my lunches and dinners have more veggies than this but since this is all that's available it will have to do today."