It's not CICO. It is fasting.
CICO is not a thing because a body is not a fixed machine, like a car engine made of steel. The body is malleable and flexible. It reacts to stimuli. When you reduce calories, your body:
It adapts. Worse, your Set Point gets changed. Now, if you go back to the calories you used to eat, you'll now gain weight. If you keep restricting calories, you'll crash your metabolism. This has been studied at length with the Biggest Loser diet.
Fasting is about getting the right hormones in play at the right times. If you can get into a catabolic state with low insulin, your body will happily eat your body fat for fuel night and day, and heal your body like you are on some super drug. It's not "starving" if you have tens of thousands of calories on your body.
As you might imagine, there are some rules of the road to do it safely. Research Dr Jason Fung and Dr Mindy Pelz on YouTube. The sweet spot to work towards is "rolling 48s".that is, having a nutritionally dense meal every 48 hours. All other times it's just tea, water, and electrolytes.