So, fasting this long is only possible if you have a lot of weight for your body to somehow cannibalize?
Excessively fast weight loss can cause liver injury. Most obese people will already have some degree of fatty liver disease (NAFLD), and while gradual weight loss is beneficial in reversing that liver disease, excessively fast weight loss can have the opposite effect and promote liver disease progression.
Not only is it throwing off hormone/endocrine production, the toxins that have been stored in the fat cells are all being filtered through the body at the time of breakdown.