Years ago we used to think that walking burned the same number of calories as running. Moving a body mass from point A to point B takes the same amount of energy. If you run, you will burn calories at a much faster rate but for a much shorter period of time. The magic number we always used was 100. A person of average size burns 100 calories per mile. Were we ever wrong!

The first thing you need to know is total calories burned is not what matters, especially for weight loss, because that figure includes your basal metabolic rate (BMR), or the number of calories you burn whether you are exercising or not. An average 150 pound male has a BMR of approximately 1,600 calories burned per 24 hours, or 63 per hour.

Weight loss is dependent upon net calories burned, or total calories MINUS basal metabolism. So forget that number you see on the treadmill- more than likely that number is significantly higher than your net calories burned because it includes BMR calories. According to the figure above, the 150 pound guy must subtract about 32 calories from the total number burned every 30 minutes.

The second fact you need to know is that walking burns fewer calories per mile than running, unless your walking speed is very fast (12 minute miles or 5 mph). Running involves more up and down movement than walking and therefore requires about 50 percent more energy.

Researchers at Syracuse University have come up with a formula to estimate net calories burned for running and walking:

Running .63 x body weight (lbs)

Walking .30 x body weight (lbs)

Here is the shocker. Say you weigh 150 pounds and lie to walk for exercise. Multiply 150 x .3 and you get 45 net calories per mile. In order to burn off just 1 pound of body fat (equal to 3,500 calories) you need to walk 77 miles (3,500 divided by 45)!

Do not be discouraged! Walking is still the most popular form of exercise for weight loss and research supports its many benefits. For effective weight loss, all you need to do is find a way to cut 300 calories a day out of your diet and burn an extra 200 net calories (about 4.5 miles of walking a day). That should enable you to comfortably lose 1 pound a week.

Remember, that 4.5 miles does not have to be all at once. All of the walking you do throughout the day counts toward your total.

If you walk 20-30 minutes a day, now you can see how tough it will be to lose extra weight without a change in diet!