How much time on tredmile do you need to lose a pound?

"Losing a pound" is a very general statement. Your body will lose water very quickoly when walking. Most do not want to lose muscle tissue. I can only assume you mean a pound of fat. A pound of fat contains about 3500 calories of energy. The only healthy way to lose fat is over time. From a "math" perspective, to stay on a treadmill until you lose a pound of fat, would likely mean walking on a treadmill for six to eight hours. There's more to it than that, though. After that much time on the treadmill, you will likely become seriously dehydrated. In addition, you would have burned all the sugar in your bloodstream and your body would likely start burning muscle for energy, rather than fat, in that kind of extreme situatioin.

While there is no way to predict exactly how your body will precisely react, a person who has a calorie intake of 250 calories per day less than their basal metabolic rate (roughly 8 calories per pound of body weight), eats wholesome food, makes sure they are properly hydrated, and walks 3.5 mph for 25 minutes 6 days a week should be able to burn about one pound of fat, on average, per week. The heavier you already are, the more calories you will burn with the same amount of exercise.