from my experience of a severely depressed teenager. i learned that fasting in general helps with depression. but results wont come overnight.
actually first of all it will make it worse initially. but if you fast especially prolonged fasting ( not a 1/2 day fast), it will make you feel better. problem is fasting alone cant help get rid of depression and anxiety. you need other things like healthy eating, sport and activities. but fasting can do like a 30/40% helping you get rid of it.