Eating disorders are conditions, such as
Bulimia (bingeing and purging),
Anorexia (restricting food intake) and
Binge Eating Disorder (repeated and/or prolonged bouts of overeating),
where people tend to use food to help them cope with difficult emotions.
People with eating disorders use food or at least try to use food and unusual eating behaviors to make them feel better. This may or may not work in the short run, but it seldom proves successful over the long haul.
Because feelings and difficulty dealing with feelings are center stage with eating disorders, they are thought of primarily as psychological disorders.
Some kind of psychological therapy can often be helpful, as can training in how to deal with difficult feelings. It is common for treatment for eating disorders to work at some point to try to help people learn how to eat moderately.
More information from the National Institute of Mental Health on eating disorders