The first is a good article by Dr. Sarah Ballantyne summarizing a number of studies that have been done with Keto and she provides a full list of references. The second is a simple list of side effects.
I think it's important to keep in mind with any significant dietary change there can be an impact on your health. Keto is a therapeutic diet and it can be useful in treating some conditions. And I think it needs to be approached with the same kind of caution that you'd approach any treatment.
If you're currently doing Keto or considering it, I'd suggest reading up just to make sure you're aware of the benefits and the potential issues.
I'm sure my friend who's into Keto and IF is going to love this as much as the cautionary IF post I did. :) Oh well. I do think fasting and Keto can have dramatic effects on health, I just think there needs to be some careful consideration and probably a conversation with your doctor.