Does fasted cardio burn more body fat over time?

Fasted cardio does not have an established automatic advantage for long-term fat loss. Using more fat as fuel during one session is a different question from reducing stored body fat across days and weeks. A small trial of young women in a calorie deficit found similar body-composition changes with matched aerobic exercise performed fasted or fed.[1]

Another trial in women with overweight found improvements with interval training in both feeding conditions. These were relatively small and short studies, so they do not settle every population or training format. They do challenge the claim that eating beforehand necessarily blocks the fat-loss benefits of cardio.[2]

The more useful choice is the one that supports consistent training, an appropriate overall energy intake, and tolerable hunger and performance. Fasted exercise can be a preference without being a superior fat-loss mechanism. Someone who feels weak or dizzy without food has no evidence-based obligation to preserve a fasting window for the sake of a physique goal.[1][2]