You can always build your way up to a fast. Begin by keeping out some foods until you are completely juice fasting and from there on less juice and more water and eventually water only.
psychologically means you have to be in an environment where you don't think about negativity. For example; worrying about the payment, non-supportive relatives or friends, bad relationship etc. Psychological issues can trigger hunger, even when you are not hungry. It's a escape for allot of people who have psychological issues.
i think your problem is more of a psychologicall issue. if you can get to the root of it i am sure you will benefit from it.