I have a friend who's weight would be at the low end of normal range. She got that way by eating an extremely low calorie/low fat diet for years.

She recently discovered information about low carbing and was interested because she was concerned about glycemic load etc. She has been eating low carb for a couple of weeks (and has added some meat, dairy etc) and is gaining weight visibly.

I seem to remember somewhere a post about the problems people who have eaten extremely low calories can have long term. Can anyone direct me to some helpful advice for her?

TIA