Sometimes anorexic individual's blood pressure can be lower than most. This may cause nosebleeds at strange times. Bottom line... if you're getting nosebleeds, check in with the doc to make sure it's not something more serious than just a bp drop. Many anorexics get persistent nose bleeds not just ana mia's, throwing up increases pressure in the venous system, and vomiting can also rupture the blood vessels in the esophagus and stomach, and cause haemorrhaging. or can cause blood vessels to pop, some ana's say they get nose bleeds more often in the mornings or when they display more normal eating habits.
Also, a lack of certain vitamins, K for one, vitamin B12, folic acid, calcium, and iron causing anemia, can cause bleeding disorders. Nosebleeds are seldom a cause for alarm but can be life threatening in rare cases. Liver Disease can interfere with blood clotting and result in frequent and/or severe nosebleeds. Try not to take asprin which thins the blood and maybe eat a rivita or rice cake with marmite as marmite thickens the blood and may prevent your nose bleeds from happening so often. I would begin to take a multi vitamin, fish oil and calcium supplement if I were you. Because vitamins do not contain calories, they have no effect on weight gain. Hope you feel better soon.