According to Spark People, a person who weighs 350 pounds can burn 320 calories if he walks two miles at a pace of 17 minutes per mile. At this pace, it takes 11 days to burn 3500 calories or one pound of fat, and 2,173 days to lose 200 pounds.
If a person who weighs 350 pounds takes two walks a day, he can double the calories burned. Burning 640 calories a day, it takes 5.5 days to burn 3500 calories or one pound of fat. At this pace, it takes almost 1,100 days, or three years, to lose 200 pounds.
Walking is an effective form of low-impact aerobic exercise. Increasing walking times and distances, plus reducing calorie intake from food consumption, speeds up weight-loss results.