How long does it take to burn body fat?

Varies with effort: Burning fat generally requires aerobic exercise. That means a slower exercise pace so that you are not out of breath and you can talk easily while walking. However recent research suggests that you can burn fat faster with alternating slow and fast paces. Do 8 min slow pace, then one minute fast pace (80-90% of max). Then 8 min slow and 1 min fast again.