Answer:
Behavioral and emotional pressures.
Step-by-step explanation:
We already know that high self-esteem would most likley not result in this, so we can kick that answer out.
A bacterial infection also wouldn't cause this, as it is psychological and emotional based.
A lack of sleep wouldn't cause this either, most likely.
In the end, we hace behavioral and emotional pressures. This is correct because often when someone goes into an eating disorder something psychological happened; whether is be peer-pressure, bullying or etc