Why does a person crave for food when depressed?

A depressed person stops caring about their appearance.  But, not all people crave food when they are depressed.  Some people actually lose their appetite and even their will to live.  

Also, the reasons for our food cravings can be very complex and people should not assume someone is depressed if they are overweight.  

Because eating raises your insulin, which lowers stress hormones

Only people who are willing to 'heal' crave food when depressed since familiar routines that remind us of our overall blessings help restore some of our emotional well being. The body itself is satisfied which reduces stress. The truly self-destructive stop eating or even forget to eat and lose a desire for it. 

it's there when nothing else is.

It's a way to feel comfort. 

The term "comfort food" actually means something.