Liz Neporent is a diet and fitness expert and author of 12 fitness bestsellers. She regularly appears on national TV programs and is the president of Wellness 360, a New-York based wellness provider. You can also follow her on Twitter @lizzyfit.

Photo: Jervis_Pics, Flickr

Walking a mile burns the same number of calories as running a mile -- fit or fiction?

Well, this one is not so clear-cut. The answer is no, yes and it depends.

Walking at moderate speeds burns up to 40 percent fewer calories than jogging at moderate speeds over the same distance. This is because moderate walking is a more efficient way of moving and involves fewer muscles than running at a slow-to-moderate pace. When you walk, your legs are fairly straight as your foot strikes the ground. There is less impact, and your center of gravity remains relatively constant. All this conserves energy, e.g., burns fewer calories. Running is essentially jumping from foot to foot which is less energy efficient than the smooth glide of walking; because your knee is bent when your foot strikes the ground, muscles use up even more energy acting as shock absorbers and gravity fighters.

An American College of Sports Medicine study from 2004, for example, measured the calories burned running and walking over 1600 meters (around a mile) on a treadmill for 12 men and 12 women. The average calories the men burned running was 124 and 88 calories burned walking. The women burned 105 and 74 calories respectively. That's a 30 percent difference. (The men burned more because they weighed more.)

However, running doesn't always burn more calories than walking, and once again, this has to do with efficiency of movement. If you jog at a slow, barely-pick-up-your-feet pace, you'll burn a respectable 8 calories per minute -- but walking at a pace that is so speedy you have to wiggle your hips and swing your arms madly to keep yourself from breaking into a run can burn a massive 15 calories per minute. The so called "cross over" or "gray zone" pace, where walking becomes very strenuous, occurs somewhere at around 4 to 5 miles per hour for most people. So in other words, a 150-pound person running a mile at a 5 mph might burn 96 calories and 180 calories walking over the same distance and at the same speed.

To make things more complicated, you need to consider fitness level, hills, surface type and a host of other factors, all of which will significantly affect how many calories you burn over a given distance and a given amount of time. And to really complicate matters, a University of Colorado at Bolder study found walkers burn more calories walking at super-slow speeds (2 miles per hour or slower) than they do at moderate paces, due to the inefficiency of holding yourself back from using a normal gait.

If this is confusing, let me simplify it for you. Walking has the advantage of being easy to do and virtually injury free whereas running typically torches more calories but is tougher on the old joints. For most of us, a mix and match approach probably yields the best results. Just get out there and move your fanny. In the long run -- or walk – it's all miles in the bank.

I'd love to hear from you. If you have a question or you want to share your workout tips with the rest of the community, leave a comment or tweet me on Twitter.