Most people believe that walking one mile and running one mile burn the same number of calories. You know, a mile is a mile is a mile. Sounds reasonable, but is that really the case?
Not so much. In fact, running more than doubles the amount of energy you expend versus walking, according to research published in the journal Medicine and Science in Sports and Exercise. A 140-pound person burns 13.2 calories per minute running, according to the American Council of Exercise. That same person would burn 7.6 calories per minute walking. We’ll do the math for you: in a 10-minute mile, that works out to 132 calories burned running compared to 76 calories burned while walking.
Here’s what’s happening in your body when you’re running and walking: “muscle action that propels you from point A to B requires the utilisation of a thing called ATP,” explains Janet Hamilton, an exercise physiologist and running coach with RunningStrong. “Your body stores only a limited amount of ATP (enough for only a few seconds of activity), so it needs to replenish that supply, and it does so by metabolising your stored fuels (glycogen and fat). The process of making useable energy (ATP) from stored fuel (glycogen and fat) is dependent on how much you need and how quickly you need it.” So the more intense the activity, the greater the demand for fuel—and since walking is less intense and demanding than running, it doesn’t demand that ATP be produced at the same rate.
To estimate the amount of energy—remember, energy equals calories—the body uses during physical activity (versus when you’re at rest), scientists use a unit that measures the metabolic equivalent for task (MET). One MET is what your body burns while lounging on the sofa watching Netflix. Walking, a "moderate" exercise, uses 3 to 6 METs; running, which is typically classified as "vigorous," uses 6 METs or more.
Running also has much higher “afterburn” (or excess post-exercise oxygen consumption) effect than walking—meaning, your body will continue to burn calories after you’re done exercising until your body returns to its normal resting state. Research published in the The Journal of Strength & Conditioning Research found that the afterburn lasts five minutes longer for runners than it did for walkers.
That’s because the body requires energy to recover from exercise. “The greater the intensity and volume, the more calories will be burned after the exercise is completed,” explains Iain Hunter, a professor of exercise sciences at Brigham Young University. When exercising, you burn some of your stored fuels; replenishing those stores takes energy. Your body uses energy to repair any microdamage from exercise as well. Plus, “along with caloric expenditure, there are many other benefits to higher intensity exercise, such as increased bone density, improved strength and endurance, more resilient cartilage and other tissues that degrade over time, and psychological health.”
From a weight loss perspective, running is the clear winner: When researchers compared 32,000 runners from the National Runners' Health Study with 15,000 walkers from the National Walkers' Health Study after about six years, they found that calories burned through running led to 90 percent more weight loss than calories burned through walking.
Fitness trackers and fitness equipment can tally your calories burned while exercising, but they’re not always accurate. “Using a variety of sources and taking a ‘midpoint’ might help keep you honest,” says Hilaton. “I think it is important to keep in mind that all of these estimates of calories burned are just that: estimates. There are a lot of variables that go into the actual number of calories burned by any given individual in any exercise beyond speed and duration.”
Can you up those numbers? The more you weigh, the more calories you’ll burn, no matter the activity—that’s because it takes more energy to move more weight. If you’re specifically looking to up calorie burn, adding a 20-pound weighted vest would up your calorie burn to 8.7 and 15.1 per minute for walking and running, respectively. It’s simple physics: “the majority of calories burned in running [or walking] comes from supporting body weight while moving up and down,” says Hunter. “With more weight, there will be a greater energy cost in doing this due to a greater gravitational force.”
The same goes for intensity, too: hiking or climbing stairs can actually bring your walking METs burn up to running levels. “Greater muscle forces are required to move faster to accelerate the body up and down, move the limbs faster, and work against gravity,” says Hunter. “Running or walking uphill requires a greater energy, just like lifting weights upwards. It’s as if our body is the weight that we must move to greater heights, so the greater the slope, the greater the energy requirement.”
And then, of course, there’s speed: “speed has a huge effect on caloric expenditure,” Hunter says. “The faster someone runs, the more calories they will burn per minute. However, by distance, there is a relatively steady amount of calories burned.” For example, in 30 minutes of running at 6 miles per hour (that’s a 10-minute mile pace), a 155-pound person will burn 372 calories. At 6.7 mph (or a 9-minute mile), they’ll burn 409 calories, and at 7.5 mph (an 8-minute mile pace), they’ll burn 465 calories. To double your calorie burn per mile, you’d have to literally cut more than 4 minutes off your pace, which is a huge amount of time. (Fast walking can actually help you raise your calorie burn to the same amount as what you’d burn jogging, in fact.)
But just because it isn’t as time- or energy-efficient as running doesn’t mean you should never look to walking as exercise. Whether you’re running or walking, you can reduce your risk of hypertension, high cholesterol, diabetes, and improve your cardiovascular health, according to data from the National Runners’ Health Study and the National Walkers’ Health Study.
“I like to say that running is a gift. Not everyone gets that gift. If you’re one of the ones who has been gifted with the ability to run and enjoy it, then treasure that gift. Nurture it and never ever take it for granted,” says Hamilton. “But walking is a wonderful activity and for those who don’t have the ability or desire to run, it can provide huge health benefits. The difference in calorie burn between briskly walking a mile and slowly running a mile is minimal—the more noticeable difference is how long it took you to cover the distance. Walking builds and maintains lower extremity and core strength, helps clear your mind, and, for runners, it’s a great way to have an active recovery day.”
In the end, vigorous running wins out for calorie burn, but remember that calories aren't everything. Obsessing over exactly how many calories you consume or burn is just as unhealthy as not exercising at all. So choose the activity you love most—whether it be walking or running—and focus less on the calories and more on how much better you feel after doing it.
A version of this article appeared on Runnersworld.com