I would highly recommend Dr. Joel Furman's book "Eat to Live" to you! Some people on this forum have already been discussing it and it seems as though a lot of us have already read it and are applying this to our eating lifestyle. If I were you I would not go on a long Water Fast because you are so tiny already. But Dr. Furman's book is all about eating fresh fruit and vegetables, legumes, nuts and beans. You will become extremely healthy if you follow his advice completely and don't veer off course! This book will educate you about your health and how different foods interact in your body. At the most maybe Water Fast for a short time, but eating a completely plant based diet will help your body to heal as well. Good luck. Keep us posted on how your recovery goes.