Hi, I also have bipolar disorder.
Did you know that they cured 7,000 Schizophrenics in Russia by making them water fast for 25 days? They took them off meds within the first 5 days. You can do a Google search about this.
Anyways, what I am doing is ADF–alternate day fasting. What I do is I eat one large balanced vegetarian meal every 48 hours. And during those 48 hours I only consume water.
This way you lose some excess weight, preserve and even build muscle mass, as well as have a feast every other day. This method has in fact cured the constipation problem I faced for the past 8 years.
I am doing research on myself basically. Feasting and then fasting has allowed me to build a lot of inner strength and taken me out of the deep depression I faced for the past 6 months.
Essentially, for the past 6 months all I did was sleep all day long, like a typical bipolar. The goal in doing this should not be quick weight loss but rather getting healthy. When you feast, you naturally boost all of your neurotransmitters such as dopamine and serotonin. And when you fast, your body detoxifies and has a chance to generate new nerve cells with greater immunity to depression (and mania) in the brain.
So instead of extended water fasting or juice fasting, I suggest alternate day fasting. This will clear up any imbalance in brain glucose metabolism so that your moods will not only become stable over time but you will feel happy when you eat as well as when you fast.
I would also add that it is crucial to take daily warm water enemas which will clear fermenting material from the colon. This also magically lifts depression.