The De Ronde is the top event imho for cycling in the world and did the sportive yesterday ! This was it https://www.strava.com/activities/1481561808
Now note this at breakfast no food so did this so fasted with sone jelly babies during it and felt great !! Climbs were so strong !! And again shows the power of fat adaption !
after this effort I ham now doing super low MAF efforts of between 105-120 when MAF is 135 and simply this is to aid recovery and create an even bigger aerobic base …
Seems to be working looking at average BPM vs NP
Ian - Have you ever tried drinking ketones on rides as fuel? Just wondering about ketone levels in blood and power output for climbing.
Mark
nope far too expensive for me to try that TBH but would be an interesting experiment to find out
and then I did this ride as mentioned in the piece below and even a pic of me !
I take it you didn’t do the whole thing fasted? Well done either way! I am slowly building up the miles after a foolish few years off the bike after a back injury and associated BS, hope to have a bash at a 100 miler at some point. 
Started fasted but topped up on the way with whatever I could get, on such a ride no one should worry about carbs
Now I am having problems with dizziness when going hard. Any thoughts on glucose levels in blood? Mine has been pretty low: Glucose 68-80 while ketones are1.5ish.
Mark