Here’s an article on keto from a medical journal https://www.atherosclerosis-journal.com/article/S0021-9150(1...
Even the experts debating here aren’t contesting the role of insulin in weight loss, but rather the secondary effects like those on LDL. Here in turn is a talk by a doctor from UC Berkeley explaining more about that:
https://www.youtube.com/watch?v=7gZt9DQqtZI&t=217s
From what I can tell, the sole focus on calories is the result of early misunderstandings and oversimplification of biochemistry in 1980s nutritional science.
Anecdotally, I did a 3 month experiment where I increased my calories (lots of olive oil, avocado, nuts, butter, etc) but consuming almost no carbs (and mostly carbs from vegetables) and I lost 8 notches off my belt.