koala logs

That actually works. But just to be clear, this is zone 2 in the 5 HR zone model, NOT the three zone model. Below tempo and should still feel relatively easy. Sweating but not sweating like rain.

But to have any fat-burning effect, the z2 ride or indoor training should take at least 2 hours and avoid doing intervals harder than z2.

Don't do fasted training into the tempo zones or higher. This will switch your body into protein-burning mode and that will cost you in recovery and muscle development.