How Many Calories Do You Burn Running a Marathon?

It is generally accepted that an average, hobbyist runner burns roughly 100 calories per mile run.

As a modern marathon is over 26 miles, you’d expect a marathon to burn 2600 calories, and within certain bounds, this is more or less what we find.

There are mitigating factors, though – height, age, weight, general fitness, metabolism, the particular course of the marathon, etc.

For instance, while to some extent people carrying extra, unneeded weight as stored fat will work harder simply because they’re carrying it with them, the additional calories burned will probably not match the perceived extra effort.

Meanwhile, it’s actually muscles that burn calories faster because they need the energy to work, so those without extra stored fat will actually experience a need for more burned calories to power their muscles.

Marathons that remain on the same level of elevation above sea level will burn fewer calories than those which include significant periods of incline because the body works harder to push uphill than it does to move on a horizontal level.

And above all, there is the question of consistency of speed and effort. It is unlikely that any marathon runner will maintain speed and pace over all 26 miles, so there will probably be some fall-off in calorie burn across the length of the course.

Experienced runners tend to claim a calorie burn of 2500, rather than 2600 across the course of a marathon, to comfortably mitigate all these fluctuation factors.    

How many calories do you burn running a half marathon?

Given that the average calorie burn of an average runner works out at around 100 calories per mile run, and a half marathon equates to 13 miles and change, you’d be within your rights to assume that a half marathon would burn around 1300 calories.

And on average, you’d be more or less right. But there’s very little precision in this calculation – it is at best approximate math.

Runners tend to allow for a burn of anything between 1100-1600 calories during a standard half marathon, because no two half marathons are exactly alike, even for the same runner, let alone for any runner that runs them.

It’s been equally estimated that, for instance, a 100-pound runner who runs a half marathon in two hours burns only around 900 calories, while a 200-pound runner, running the same marathon in the same time, burns around 1900.

The number of calories burned will fluctuate – usually within the 1100-1600 bracket – depending on the course of the half marathon too. More hills (uphill and downhill) will increase the calorie burn compared to a relatively flat 13 miles.

This will especially be the case if there’s an appreciable change in altitude over the course of the half marathon, because higher altitudes force the body to work harder for its oxygen, and will release more calories from stored food or fats to power the muscles.

And it’s important to consider the consistency of effort, too. As with 10Ks and full marathons, running 13 miles consecutively is not the same as running 13 separate 1-mile stints. Pace will fall off in some places, and calorie burn will follow it.

How many calories do you burn running 10K?

Calorie burning through distance running is dependent on a lot of factors, and each of those factors will skew the answer. Height, weight, general condition of health, speed of the run, metabolic rate, etc, all play a part in arriving at your final number on how many calories you’ll burn running 10K.

With this flexibility and allowing for personal variation though, there are generalized figures that can be of some use to us.

The ‘average’ runner – by which we mean you if you have any job other than ‘athlete’ – is usually said to burn 100 calories per mile run. If we’re dealing in kilometers rather than miles, a 10k run is equivalent to just over 6 miles.

That means 100 calories per mile, multiplied by 6 – which is 600 calories, roughly, that the average runner burns during a 10K run.

There’s a vexed question over whether heavier people burn more calories through running than lighter people. And the answer to that is sometimes yes, sometimes no.

If you have people of vastly different weights doing the same exercise with the same intensity, then technically, the heavier person would burn more calories from running 10K than the lighter person, but only because they’re physically carrying around more weight per step than the lighter person.

Perversely though, stored body fat is just that – stored. It’s relatively idle, and it doesn’t burn calories because it’s not doing anything.

So in terms of burning calories, those with more muscle density tend to burn more calories in everyday running situations, because their muscles need the energy to function more. 

How much sugar do you burn running?

Researches have shown that when we run, more than 50% of the energy we use comes from bodily sugars, released as calories, and used by our muscles and other bodily systems.

It’s not quite as simple as that, though. Our bodies have two fuel sources – fat and sugar. For reference there are 9 calories in a gram of fat, and only 4 calories in a gram of sugar.

Unfortunately perhaps, our body’s immediate go-to when we start to run is not the high-calorie fat, but the low-calorie sugar. This is especially true of high-intensity exercise – the higher our heart rate goes, the more sugar we burn.

That adds a complication to our answer. It will change depending on what kind or running we’re doing. Sprinting – high-intensity running over short periods? Our sugar burn goes up. Marathon running – relatively low-intensity running maintained over long periods? Our sugar burn goes down and is subsidized by an eventual fat burn.

On that rough basis, knowing that average long-distance runners burn in the region of 100 calories per mile consistently run (which is to say, run for distance, rather than for a burst of sudden speed), if we assumed all of those calories were burned in sugar, it becomes a simple – if highly approximate - equation.

100 calories, divided by 4 (the number of calories in a gram of sugar), means we burn 25 grams (or 0.88 of an ounce) of sugar.


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