I didn't mention anything about the First Law of Thermodynamics... and I am well aware of the argumentation around it.

However...the basic premise is still true. Calories do matter (even though it's not as simple as the equation "eat ... calories less than you burn and you'll lose weight").

And even well-respected scientists in the keto-sphere say that calories matter (when in doubt listen to a few podcasts with Dr. D'Agostino or Ben Bikman).