Which cardio is best for losing fat ? Your body uses both carbs and fats for energy. The intensity of your workout determines which is used more. High-intensity exercises like running or weightlifting primarily use carbohydrates because they provide quick energy. Low-intensity activities like walking rely more on fat. But burning more fat during exercise doesn’t equal more fat loss. Your body compensates: if you burn more fat during the workout, you’ll burn more carbs later—and vice versa. So wh