The speed at which you walk is important for weight loss. However, the distance you walk is equally important in losing belly fat. A regular, slow walk will burn about three quarters of a calorie per kilogram of body weight. This would be about 70 calories a mile if you weigh 200 pounds. A fast, brisk walk will burn about 125 calories a mile if you weigh 200 pounds.
Research has shown that walking 10,000 steps each day will help you lose around 500 calories per day. If you do this every day without changing your diet, you will lose one pound of body weight per week. If you want to lose belly fat quicker, you must cover a longer distance or increase your speed to lose more calories.