Scientists discovered that HGH levels peaked to as high as 2000% from the baseline right at the 24 hour mark of the first day. From what I understand the most efficient way to increase your HGH levels naturally without using any drugs is fasting.
I have seen it aswell. And I have been on IF since 1st january. So far love it, I feel more energized thru day and fasting actually saves alot of time.