And burn it does. The high dietary fat is oxidised for cellular energy in the normal fashion but winds up generating quantities of Acetyl-CoA that exceed the capacity of the TCA cycle. The significant result is ketogenesis - synthesis of ketones from the excess Acetyl-CoA. In more lay terms: the high fat intake ''forces'' ketosis upon the body. This is how its 'done right'.
https://goldencondor.org/keto-belly-burn-fat