The amount of fuel is counted in terms of calories, which we consume in our food and then use up through the various functions (both conscious and subconscious) that our body is asked to perform. If we were to lie in bed in a totally sedentary state we would need about 20 calories / kg that we weighed just to live - for our brains to function, bodies to keep warm, blood to keep pumping etc.

On top of this we need to provide calories for all the activities that we undertake, whether it be walking from the kitchen to the living room or running a marathon. Clearly the number of calories that we need will be dependent on how much activity we do.

For an average person (whoever that may be!) the following calorie intakes are recommended

• Men 2500 calories
• Women 2000 calories

This would be for a person of average weight who does an average amount of exercise. As you are interested in running, it is likely that you do more exercise than the normal person.

Photo Man running on beach

To help with this the following guide can be used (it is only approximate, but serves pretty well).

For each mile you run you will burn about 1.6 calories for each kg you weigh.

This means about 100 calories if you weigh 60kg or 130 calories if you are 80kg.

Surprisingly, this doesn't depend too much on how fast you are moving, provided that you technique remains the same at all paces (for example if you lift your body up and down more at a fast pace you'll use more energy). However, those who run faster clearly have time to do more miles and therefore use more calories!!!

In terms of considering your weight - this is fairly straightforward in concept (but a lot tougher to control in practice - as the multitude of slimming products on the market pays testament to).

Calories In = Calories Out = Static Weight

If you eat more than you use, your weight goes up and vice versa.

What does this mean in practice?

As a runner you need to decide what your ideal racing weight is - which is a very tough question and not one we would want to attempt to answer here. Then you need to get to it / maintain it. Do this slowly, as you are putting your body through tough exercise and changing weight dramatically whilst doing this is likely to leave you ill or injured. We'd suggest no more than 1kg / fortnight for weight loss and probably only half of this at the most for weight gain (which you want to be muscle not fat in most cases).

It is very easy to get caught up in counting your calories and not enjoying your food. We suggest you don't get carried away with it, but maybe have a look at your dietary composition over the course of a week, recording everything you eat in a food diary, and then review it to see if you should be making any changes.

Here it is also worth mentioning RED-S (Relative Energy Deficiency in Sport) formerly known as the Female Triad, but now recognised to affect men too. This is where not enough energy is consumed over a sustained period of time for the athlete to do the training they are asking of themselves. This can be career ending, particularly if you end up giving yourself osteoporosis - many athletes have later regretted this and we've known some go on to become sports nutritionists specifically to try to stop this happening to others. Please investigate fully what this means and how you can avoid it.

The information here is written by an athletics coach who has read widely into the subject and not a sports nutritionist, so is about gearing your food and drink to the practicalities of running.

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