I’ve done keto a couple times in the past, even back when it was called Atkins. It absolutely was a calorie deficit diet since it was difficult to eat that many calories consistently to go over my BMR for more than a few days at a time.

Friends doing it also had the same experience as I did.

Not saying it isn’t as advertised, but everyone on it I knew (n=14 or so) was getting results from fewer calories after we all decided to start carefully logging food intake.

It’s a great diet that works, but via other mechanisms for many vs ketosis.

It’s still a restriction diet that poses a lot of challenges for most to remain consistent with on a long term basis.