This was before all that. I couldn't even find a book. I found Keto by going through every diet subreddit and looking for which ones had the most before and after photos that were significant, and not sponsored by for-profit programs (like weight watchers).

Intermittent fasting seems similar at the moment. Promising results, and I can't find a sponsor. Sure, given any trend, people will find a way to make a profit. But the kernel of these seems fairly organic, unlike say, the "South Beach Diet."