Well, I know this doesn't help much, as it is anecdotal, but my brother who is just gone 41 has been struggling with his weight since he was a teenager. His preferred kind of diet was the fast, he would stop eating for two to three days at a time in order to lose weight.
3 or 4 years ago he found out he had a thyroid problem and the fasting had made it worse. It has now been removed and he is on drugs for the rest of his life. He would have had the thyroid problem one way or another, but he made it much worse by fasting every couple of weeks. We know he also used to purge when he was younger and possibly could have continued later on in life (just become more clever about hiding it).
TL:DR - Fasting in my experience makes any problems you may have that are latent worse.