The amount of calories you burn in a 2.5-mile run depends on many factors, including your age, gender, fitness level and body composition, according to dietitian Ellen Coleman. Other factors include your work intensity and duration of the run.
Basal Metablic Rate
Basal metabolic rate, or BMR, is the number of calories you burn while at rest, according to Coleman. The more muscles and connective tissues you have, the more calories you will burn, which also affects how many calories you burn during exercise. Your BMR makes up about 60 to 70 percent of your caloric expenditure daily. For example, if you have 175 lbs. of muscle, you will burn almost 2,100 calories a day without taking exercise into account.
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Duration Per Mile
The duration of your run and your weight affect the number of calories you expend, according to exercise physiologist William McArdle. If you weigh 105 pounds and you run at a rate of 9 minutes per mile, you burn about 9.1 calories per minute or about 82 calories. Take this number and multiply it by 2.5, and you get 205 calories for a 2.5-mile run. If you weigh the same and run at a rate of 6 minutes per mile, then you burn about 11.8 calories per minute, or 70.8 calories. The equates to 177 calories for a 2.5-mile run.
Although you burn fewer calories theoretically during a faster run, the number of calories you burn after exercise is much greater than a lower-intensity run, according to McArdle. This after-burn effect can last between one to four hours longer than a low-intensity run. Therefore, the net calories you burn during and after a high-intensity 2.5-mile run is greater than a low-intensity run.