The nurse doesn't necessarily speak for or echo the sentiments of the doctors they work for. When I first started low carb, I mentioned it to one of the nurses at my doctor's office and she was horrified and went off on me about "all that fat" and "you'll be having a heart attack in no time", etc...yada yada yada.
Then I asked the doctor about it, actually more told him, "I'm going to try low carb". His response was "If you think it's going to help, go for it!".
You should have seen the look on the nurse's face...you would have thought she just started sucking on a sour persimmon!