Given the observational evidence that it doesn't work, what are you really asking?
Imagine a computer with a primary source of power, and a backup supply. You're measuring CICO of the primary supply. And you're tightly regulating the power available on primary to keep a power deficit. Unfortunately, during periods of high load, this computer is able to switch to the backup supply which you aren't able to exert tight control over.
There's a huge number of things that could cause a human to ignore their best interests. Ignorance to consequences, the long-term implications of any decision, degraded mental health, external social pressures, the list goes on and on.
Humans have impulses just like every animal, and proper training can convince a dog not to immediately lunge and eat every morsel of food they can smell. but it takes a lot of work and external pressure to train that into a dog, and even then given the right circumstances a dog will still eat food above their caloric needs. Humans behave the exact same way.
> it's easy for me to regulate my weight using cico, so obviously it should be easy for everybody
I know that's not the claim you're making, but it seems like it is and it is the one many other people in this thread are making. just like it's easy to train some dogs than it is train others. it's easier for some humans to control their caloric intake than it is for others.
CICO doesn't work for most humans. Claiming otherwise is on par with the saying just run this IOS app on Android it's easy it works for me! Perhaps a sufficiently capable engineer could make it work, but most humans aren't sufficiently capable.
> Given the observational evidence that it doesn't work
I think you need to be very careful about your language choice here.
Physics says it has to work. Every athlete on earth knows it works. Everyone that has ever been in a prison camp, concentration camp or had their calories restricted outside of their control knows it works.
It absolutely, factually, 100% works. Our entire understand of mammals and energy depends on it working.
What you are saying, is that people are unable to exercise enough self-control to actually consume less calories. If they did, it would work. But they don't.
That's like saying "pointers in C don't work" because when many people try they get seg faults.
I really don't think it's constructive to say "CICO doesn't work" when what you mean is "many people find CICO difficult to implement, because having the self-control/will power/determination/control to do that is hard."
I became heavily involved in weight watchers (which is essentially just CICO - their "points formula" is basically calories/50). Over many years I watched hundreds of people lose hundreds of pounds by being careful about what they ate. It was hard. There were a lot of tears, there were a lot of false starts and plateaus and hard times. The people that stuck with it had incredible transformations and live different lives now. My room mate at the time lost almost 200lbs and became head of the WW in that city and when I saw her after 10 years I did not recognize her at all, and actually refused to believe it was her for 5 minutes.
CICO absolutely works. Like most things worth doing in life, it's hard. And it's worth it.