Understanding the energy requirements (i.e. how many calories you burn) when running can be useful for a range of reasons.
Many people start running for weight loss. They combine exercise with a diet plan in order to achieve a goal weight. Understanding how running contributes to this goal can help such runners adjust their food calorie intake so that they achieve a desired calorie deficit.
It's especially useful in helping to avoid over- or under-compensating for exercise.
If you're trying to lose weight then be sure to avoid large deficits, otherwise a reduction in performance (and potentially health) can occur.
If you're hoping to gain weight, then keeping tabs on extra energy requirements is crucial. Especially during periods of high mileage, it can be hard for some people to make up energy deficits. Planning ahead can make this task much easier.
In order to promote recovery it's important to refuel properly, especially after harder or longer sessions. It's ideal for some of this refuelling to take place as soon as possible after the run. The remaining energy deficit can be made up throughout the rest of the day, either before or after the run.
Energy intake can be increased prior to a run, especially leading up to harder or longer sessions, in order to ensure that enough fuel is available. However, assuming you're not fasted, you should generally have enough energy available to complete most workouts without increasing food intake.
Beware of eating too much immediately before a run. It's unlikely to cause any major problems, but can provide for an uncomfortable experience.
How It Works
This calculator is based on the concept of METs. MET stands for Metabolic Equivalent of Task. METs are used to calculate how much energy is expended for a particular task, taking a person's weight and the duration of the activity into account. A single MET is roughly the amount of energy required to sit down and do nothing. METs for other activities are determined with reference to this baseline. For example, running at 5 miles/8 kilometres per hour (about 12 mins/mile or 7:30 mins/kilometre) requires approximately 8.3 times more energy than sitting still and doing nothing. So, this running speed is equivalent to 8.3 METs.
METs and Calories (kcals)
Conversion from METs to Calories (kcals) is achieved with the following formula:
Calories/kcals = activity (METs) x weight (kilograms) x duration (hours)
So, the number of Calories/kcals required for a 6 MET activity performed for 1 hour 30 minutes by a person weighing 70 kilograms is:
6 x 70 x 1.5 = 630 calories
To determine the METs for running at various paces/speeds, we use the values provided by the 2011 Compendium of Physical Activities Reference List for Running
In the case where METs are not available for a specific pace/speed, we use linear interpolation to derive a suitable MET value.