Oh, there are health benefits associated with fasting - if you have health issues. And only the right issues, and only if done right. It's like gluten: if you're allergic to it, not eating it will make you A LOT better. For everyone else, it doesn't matter much.
The thing with fasting is, that it has a systemic impact and thus influences many things, especially blood sugar. And there are plenty of people with one problem or another that can be influenced by fasting.
And thus, people declare it the new miracle cure for everything. Which is dumb.