I do think fasting definitely helps with Depression long term and even short term.
However, I think if you are detoxing some really potent stuff from your body you can go through swings in emotion and or react to detox effects that show up externally or what you are processing internally. You are better once you are on the other side of the cleansing.
It would help if you found out what perhaps might be causing your depression. While it can be internal from bad diet , bad attitudes, it can also be caused by job stress, toxic friends and or relationships. If you find the news depressing, turn off the tv, and or leave the room. Find ways to refocus on things that are positive. If you have toxic friends, think about having less contact or let them go.
Think about positive affirmations- there is a forum for that on curezone. Also read many a post on the benefits of EFT ( haven't tried it) but heard many good things about.
Watrfasting and changing your diet to wholesome raw healthy choices will make big improvements. M any people do not even realize how many chemicals they are drinking with diet drinks , or the loads of Sugar that come in various forms from gum , salad dressings, diet /regular sodas etc... These chemicals have subtle to profound effects on the body. Water Fasting will give you a new start at renewing your health and starting a new lifestyle that counts.