Please be more specific in who "they" are.
There is no such thing as a "science application for anorexia".
Anorexia can affect anyone, but most commonly is seen in girls and young women in middle- and upper-class families.
anorexia most commonly affects teenage/young girls and women who are quiet, shy, well behaved and high acheivers at school. but lots of people can get anorexia...men, women, different ages.
Yes, anorexia can be deadly. In fact, around fifteen percent of all anorexics will die either directly from or due to a side effect of the disorder.
Muscle dysmorphia, and / or anorexia athletica.
Yes, roughly one in every 250 people are anorexic.
It can be. With anorexia, hair can become more brittle or fagile, fall out, thin, become lank, or lose its "shine" due to lack of nutrients. Dry, flaky skin is also a side-effect of anorexia. Together, they can make it look like "dry" hair is a consequence of anorexia.
The lack of eating can harm and effect the functions of the stomach, intestines, and bowels.
Muscle dysmorphia Anorexia athletica
it stresses your friends when they are trying to help you get better instead you are pushing them away
If you are anorexic, then you lose all muscle mass in your body, so your athletic abilities will be decreased.
The scientific name for anorexia is Anorexia Nervosa.