There are a variety of fads and trends that will show up every once in awhile within the fitness industry. Something like intermittent fasting could be easily seen as something of that sort.
However, it seems that the research that has been behind any kind of fasting dates back decades and centuries.
Going into any type of fast is something that our ancestors we’re used to when we we’re developing homo-sapiens.
If you consider the difficulty that they faced in finding proper food to eat, whether that was hunting or gathering. Until farming was invented most foods was either found or killed.
That took a significant toll on our body and evolution has learned a great deal from it. It protects our body and allows our body to basically go long periods without eating while having beneficial results from it.