Congratulations on embarking on your fasting journey: it will be a rewarding one I can assure you.
In answer to your question....NO.....you do NOT need anything that will interfere with the fasting process, and for the following reasons.......
ANYTHING taken into your stomach (except pure water) will prevent and inhibit the cleansing and healing as nature intended; so you are basically on a diet......and NOT a fast.
The bowels will close down; the liver will cleanse itself as well: both through a process called Autolysis; this means the body will instinctively target and remove the toxins as a priority from ALL parts and organs of your body (by burning it up), while at the same time preserving the most vital parts with nourishment from your food reserves.
Even in cases of starvation the Brain and nervous system are not affected at all. The body has an infinite wisdom of cleansing and healing if the fast is conducted properly.
Pure water though is vital on a fast to prevent dehydration and therefore permanent damage to the internal organs. If you drink according to thirst that is fine: excess water is a burden just as excess food is a burden when eating.
You should find that any hunger you experience (and there is some)!! should disappear within the first 3 to 4 days by another process in the body called Ketosis.
This information has been gleaned from all of the experts in the History of fasting from the 1850's to the present day, from Doctors Shew, Page, Dewey, Graham, Trall, Tilden, Shelton, Jennings, Carrington and many others.
Hope this has helped.
Get back to me if you need any further help and happy to oblige.