Your post screams "SUGAR ISSUES"! I would be more than willing to bet your system is full of candida, which does not necessarily manifest as a "yeast infection", but can travel anywhere through small holes in the intestine into the blood system and thence... anywhere it likes. Yeast can take up residence in your brain, causing "foggy brain", sluggishness etc. If you crave fruits (which are basically sugar) and carbohydrates, you are feeding the yeast in your system, which unceasingly calls to be fed -- and you are obliging by filling your system with exactly what it needs to spiral out of control.
Until you deal with this issue, you will never lose weight. Unfortunately, what you need to do is cut the little rascals off, and do a Candida Cleanse. I believe there is a good Candida Forum here at curezone with all the info. If you go to any reputable natural pharmacy, ask someone who is knowledgeable what natural candida cleanse is good, and follow the program prior to beginning your fast. You should be eating a candida DIET along with any herbal program, which means cutting out sugars and carbohydrates -- precisely what you "crave" (be aware it is actually your yeasts doing the craving, which will subside once they are under control). DO YOUR HOMEWORK on this issue, DO a good candida cleanse, which will take at least 4-6 weeks, and don't cheat! You are only feeding the beasts! You WILL go through withdrawals as they die back. You will feel awful! This is part of the process.
If you have never done a parasite cleanse, or if it has been a long time, look into this at the same time. Again, your natural health pro can guide you. No sense fasting, or flushing your liver, with critters living in there!
So. If you are serious enough to follow these steps, come back when you have finished. Feel free to use the Candida and parasite forums here at curezone for support while you take care of these issues. THEN we can talk sensibly about fasting. Your system is in no condition right now to cut back to juices, much less starvation diets like the one you describe. Work on becoming WELL, rather than THIN. The two really go together!
Meanwhile, pick up a GOOD book on juice fasting and study it. It should tell you which juices are indicated, and not indicated, for people with Sugar issues. Fruit is a no-no, with the exception of small amounts of Granny Smith apples... again, get the book(s) and STUDY. This is not an easy way to go, but you can learn so much about what your body REALLY needs.