I’ve been doing IF two days a week, typically Monday and Thursday. On those days I have 150-200 calories of cream + coconut oil in my morning tea, so it’s not a strict fast.
Something confuses me: on a podcast episode some time ago, it was stated (IIRC) that a paper had been published showing that each pound of fat tissue can release only 31 Kcal per day of energy. It makes sense that there would be a limit: a cell only contains so much of the enzymes needed to hydrolyze triglycerides, etc. and one of those steps in the process is going to be rate-limiting.
What is surprising is that the number is low enough that it seems like I should not be able to fast successfully. I weigh 157# and last year (when I also weighed 157#) I had a DEXA scan that said I have 13% bodyfat, so I should have about 20-21 pounds of fat tissue. That suggests I can access only about 650 Kcal/day of energy from fat. So that, plus the ~200 Kcal in my tea in the morning, would be only 850 Kcal per day of available energy. I would expect that to mean that I would feel terrible, but instead I feel fine and as energetic as on a feeding day. Before breakfast the next day (about 36 hours since my last full meal), I actually feel less hungry than I did the previous afternoon.
I really doubt I’m running on <1000 Kcal per day. So, where’s all the “missing” energy coming from? Glycogen and gluconeogenesis?
I should try a three-day fast to see if I run out of glycogen and hit the wall…