The answer to this question is that they just might, especially if you are taking a certain type of antidepressant. 

Of course there is a lot more to the story.  People gain and lose weight for a variety of reasons.  Being depressed in itself can cause great fluctuations in weight.  I know for me, I have had the experience of both gaining and losing weight while depressed.  When I am depressed and feel anxious I tend to lose weight.  When I am chronically mildly depressed over a long...