A slow, low-intensity run burns more fat than carbohydrates. During slower, low intensity runs, the higher the percentage of burned fat. So, if you run at a leisurely pace, where you could actually still maintain a full conversation, then you are probably using fat as your primary fuel. But, if you are sustaining this slow pace, then it will take longer to burn a lot of calories in total. That’s why you should work towards running at LEAST 30 minutes when running slowly. If you do it right, you’ll actually continue to burn fat even after you stop running, as your body will keep burning for as much as 2 hours after you finish…. just stick to liquids and light proteins after you run. Don’t gorge on sweets and high calorie treats as a reward for a good run.