system
Given the following post, respond as if you're commenting on Reddit:
human
An experienced runner and someone who is very out of shape run a mile. Do they burn the same amount of calories?

If we assume their weight and the circumstances of the run are the same, and the experienced runner runs slow enough for the inexperienced one to keep up, so the question comes down to: is there a difference in how efficient calories are used?
gpt
Several factors indicate the out of shape runner will burn more calories:

* the out of shape runner will have a higher heart rate while running, which burns more calories
* he will take longer to run, which means he will be burning calories at an elevated rate longer
* if he is heavier, he will expend more energy per stride
* if he is heavier, his basal metabolic rate is increased

Two factors contribute to the fit runner burning more calories:

* being fit, he has a higher metabolism, increasing basal metabolic rate
* if he is heavier, due to increased muscle mass, he will also expend more energy per stride and his basal metabolic rate is increased

Overall, the first two unfit factor can result in large amounts of extra calories burned, while the other factors are weight dependent or only impact BSM.  So the unfit runner is going to expend more calories.