You gobbled down two cookies or sipped on half of a sugary 16-ounce soda, and you want to burn it off. Running seems an expedient choice, but how far do you have to go to burn off those 100 calories?

A mile seems to be the magic number to burn 100 calories, no matter how fast or slow you go. You may burn slightly more in a mile if you weigh a lot or are very inefficient at running. But even if you blitz the distance at an elite pace, you won't burn more calories.

The number of calories you burn in an exercise activity generally depends on the time you spend doing the work, your size, your efficiency and your intensity. If you slow down while running, you do burn fewer calories each minute you run, but it just takes you longer to cover a mile – so you're burning calories for longer. For example, a 150-pound person running a mile in 10 minutes burns about 113 calories. If she slows down to a 12-minute mile, she burns 115 calories in the same distance, pretty close to the same number. She went the same distance, however – it just took longer.

If you weigh more, you do burn more calories when covering a mile, but most calorie calculators are considering your basal metabolism as well as the amount of calories you burn during the effort. Your basal metabolism is the number of calories you burn just to exist – to breathe, to operate internal organs and to think. A bigger body has a bigger engine. As pointed out by Competitor magazine, the 100 calories burned during running a mile is "net" energy burn. You're always burning calories; running a mile makes you burn about 100 calories over and beyond your norm.

Where your speed and effort over the course of a mile really matter is in the afterburn. After exercise, you continue to burn calories as your body restores itself to its pre-exercise state. It takes longer for your body to ease down following a fast mile than it does following an easily paced mile, which means more calories burned. Exactly how many calories you burn during this post-exercise oxygen consumption, or EPOC, depends on your size, how hard you ran and your fitness level.

EPOC is one of the reasons interval training is so effective at fat loss. Interval training involves alternating bouts of very high intensity with bouts of easy running. A sample interval workout might involve 30 seconds of running at an all-out pace followed by three to four minutes of walking, repeated four to six times. This protocol helped women lose 8 percent of their body fat mass after six weeks, reported a study published in a 2014 issue of Applied Physiology, Nutrition and Metabolism.

You'll burn more than 100 calories in such a running program, because you're bound to cover more than a mile. If you do take the challenge to push sprint training, it's best to not do the workout on back-to-back days. Giving yourself a bit of recovery allows you to perform each workout with your best effort and reduces your risk of injury.

Andrea Boldt earned her nutrition credentials from the Nutrition Therapy Institute in Denver, Colorado. She's also a personal trainer, master yoga instructor, run coach, group fitness instructor and Ironman triathlete.