Many people lose hair during a fast but regrow it very quickly.
Soy protein? Terrible idea. Most of soy now a days is genetically modified. Also it is not a good idea to break fast on protein and partial foods, it will only make things worse for you, by taking all necessary nutrients from your body to digest partial foods. Break your fast with a freshly squeezed organic orange, lemon or grapefruit juice. Tomato is also good. Watermelon is also used by many to break fast.
Then slowly build your appetite with plant based foods and let your body take all micro-nutrients from raw foods as well as protein.