No you will not be depressed as in I'm going to come out of nowhere and go for the save, just think happy I mean I always try to smile, also about your question with how you lost weight on depression I guess suicide watch works better then weight watchers 8D, think happy thoughts, unicorns rainbows and stuff like that, actually I never think that, but anyways all the things that will ever make you sad are just temporary and can never bring you down unless you let them bring you down.
Depression can be a chemical imbalance in the brain. Sometimes we don't always know "why" we're depressed...we just "are". There are many new meds out there for depression that can make a world of difference in your outlook on life. Thinking "happy thoughts" never really worked for me. I always felt like I was in a dark hole that I never could escape from. Finding the right medication for the depression has made a world of difference for me. Life is no longer one long struggle. Find a good doc. Who deals with depression. You CAN be happy! :D
The best way is to try to find out why you are depressed. To get to the root of the problem.