Anecdatally, on OMAD for 6 months (23h daily fast), with just espresso in the morning, and one meal late in the day, net have lost about 30 lbs. The weight loss slows down as your metabolism adapts. It is a way to get my total caloric intake down, as I just enjoyed eating too much and having to exercise discipline 3x+ a day is a losing battle. Out of sight, out of mind, etc.
Any perception of new mental clarity comes from how I relate to hunger, which I can mentally translate to a kind of excitement, similar to what some people can also do with fear. The clarity could easily be attributed to attitude and a choice that mitigates suffering. There probably isn't nutritional magic involved.
Yes, if all of this is just a way to get me to eat fewer calories, and that's all that's really happening, so be it. I've had several people scold me saying "You know you're just losing weight because of the calories, right?" and I'm like, so? Great!
I can't diet. Been trying that all my life and it's never going to happen. It's uncomfortable and socially inconvenient to be constantly weighing my food and passing up dinner invitations and never feeling satisfied. So I just don't eat a couple days a week and then forget about the rest.
Any perception of new mental clarity comes from how I relate to hunger, which I can mentally translate to a kind of excitement, similar to what some people can also do with fear. The clarity could easily be attributed to attitude and a choice that mitigates suffering. There probably isn't nutritional magic involved.