You're talking about eating for only 6 hours a day and fasting the rest?
I don't know much about insulin levels, but my experience with fasting is it's not bad and you feel fine. This is for a full day of fasting though. It just 'sucks' the first time or two you try fasting, after that it's just a breeze.
Maybe it works because the reduced time limits the amount of calories you can take in...?
If you can find one, ask a Muslim athlete about how they feel/change during Ramadan cause they only eat at night and the morning. Otherwise just give it a shot a see if it works