Personally, I wouldn't put a child on the MC. I especially would not encourage her to fast in order to lose weight!!! Instead I would go for a fresh fruit and veggie fast for cleansing purposes ONLY, and make it for 3 to 5 days at a time. With a good, healthy "pre-fast" diet of raw fruits and veggies, followed by the same afterwards, and long-term overall healthy eating, she should see dramatic results.
I wonder if she is "addicted" to anything like sugars or caffeine (soda)? And most likely, just getting her off of yeast for a month would do a WORLD of good.
I think with kids it's IMPERATIVE not to let them get into a habit of starving to lose weight. This can lead to anorexia. Please be careful as your child is still growing, and messing with the metabolism at this stage of development can be devastating long term (I speak from personal experience). A normal healthy Diet (obviously not the SAD) would be better than fasting. It may take longer to see results, but it would also be better in the long-term for the body, as well as building into your child a healthy lifestyle for the future.
The liver cleanse is most likely unnecessary at this point in time (my OPINION). I wouldn't think that a parasite tincture could hurt, but only the prescribed 7 days on, 7 days off. And with all of these natural remedies, as usual, PLEASE WORK WITH A MEDICAL PROFESSIONAL, especially since this is a child we're talking about!
God bless you both on your journey to GREAT HEALTH!