Agree there is a lot of evidence that intermittent fasting (as long as you are otherwise healthy) is of great benefit and would have been common for our palaeolithic ancestors. That said anyone looking to do it should always get as much information as possible and check with their doctor.

There are certain cases where it can be very risky. I'm a good example because I'm a type 1 diabetic (don't produce insulin) so am at high risk of developing ketoacidosis if I don't take my insulin (obviously you only take your insulin with meals) - so fasting for prolonged periods is out of the question for me.