Hyperactivity and anorexia nervosa: behavioural and biological perspective
Anorexia nervosa is an eating disorder defined by a symptomatic triad, anorexia, emaciation and amenorrhoea. This disease mainly affects young women. Besides these three symptoms, hyperactivity is often associated with anorexia nervosa. http://www.ncbi.nlm.nih.gov/pubmed/15627053
Q: I'm curious to know why some patients with anorexia nervosa (AN) develop marked behavioral hyperactivity, as in excessive motor movements and compulsive exercise, whereas others are much less inclined to be so physically active.
A: The phenomenon you describe is well known clinically, and in various series hyperactivity has been reported in 31% to 80% of patients with AN. http://www.eatingdisordersreview.com/nl/nl_edr_17_2_9.html
A possible reason related to insomnia:
Dr. Graham: poor sleep = not eating enough food "If you're dramatically under-eating, you can't expect to have a whole lot of energy. You're not going to hold your weight. You may not sleep well, because typically poor sleep is associated with not eating enough food. Your body just says 'Go look for food!' and it's more important than [sleeping]." //www.curezone.org/forums/fm.asp?i=2014784#i
Plus you can always ask her to list how many calories she's averaging a day. That would be a good clue.