Fasted cardio can change the fuel used during a workout. That is different from losing more body fat over weeks. A claim about fat burning needs to say which of those outcomes was actually measured.

Acute research finds higher fat oxidation during fasted exercise. A small four-week trial in twenty women found similar body-composition changes with fasted and fed exercise during a calorie deficit. Those are different measurements with different limits.

An easy walk and a hard interval session ask different things of you. Eating first does not cancel the benefits of exercise. Compare comfort and whether you can complete the session you actually intended to do.

Try both routines on similar, manageable mornings. Keep the route and effort reasonably consistent. Notice energy, hunger and how the rest of the day goes, instead of judging the choice from one unusually good or bad workout.

If you use medicines that can lower blood glucose or have specific meal instructions, discuss fasted exercise with your clinician. Stop when you feel unwell. Completing a fasted session is never a reason to ignore symptoms.

Choose the breakfast routine that helps you repeat useful training. In Bali, starting earlier may help with heat, whether or not you eat first. Keep the whole week in view instead of chasing a fuel-use slogan.