Ho long have you guys been on the diet?? If it is a matter of days, then what is probably happening is your body is trying to adjust from burning glucose to burning fat...My first 3-4 days of the Atkins diet were tough as far as feeling mentally "cloudy", tired, and even some stomach cramping...
Now, however...way different!! Totally the opposite as a matter of fact..Tell you friend to try to stay with it...The way she's feeling ahould pass soon...Make sure she is not trying to do a low carb/low fat thing too...Use Dr. Atkins book like it your diet bible...and soon you'll see how wonderful low carbing can make you feel!!