What factors have been identified as contributing to obesity?

Obesity, a topic that is getting much attention these
days, is obviously caused by overeating; in its simplest form, obesity is the
accumulation of many more calories taken in than expended by a person.  That being said,
what causes a person to overeat in such a way that he or she doesn't just gain a few
pounds here and there, but becomes much heavier than is appropriate?  Many experts have
identified unhealthy eating patterns as related to emotional eating; one expert, Bob
Greene, a frequent contributor to Oprah's talk show, has often said that very often,
obese people are quite literally wearing their pain.  Eating to camoflauge unpleasant
feelings, such as those related to abuse, seems to be common among many obese people, as
well as eating to deal with stress.