A strange thing happens to food when you become a runner - it reinvents itself as "fuel" or even "nutrition".

Up until now I've been following a couple of simple food rules: eat whatever I like, ditch the junk food and drink plenty of water.

To date that's served me well, but I can't help feeling that I'm missing the "fuel" part of the equation.

Running in the evening is a particular problem. I'm most likely to skive out of an end-of-day run citing "tired and hungry" as excuses.


I've also pushed past the one hour mark on my long runs and I'm not sure if this means I should be taking extra food and water with me.

Basically, when and what to eat are a mystery to me and I think my running suffers as a result.

Claire Turnbull, who runs Mission Nutrition and is the nutritionist for Healthy Food Guide, says when we are doing high-intensity exercise, such as running, our preferred source of fuel is carbohydrates.

We do have a carbohydrate reserve in our muscles, called glycogen, which will last between 60 and 90 minutes of running, says Turnbull.

To ensure I have enough food on board for longer or harder sessions Turnbull says a light snack 30 minutes or meal two hours before a run.

With the majority of people training before or after work pre-run eating can get a little bit tricky.

Morning exercisers will need to decide whether their training run warrants getting up half an hour earlier and having a snack of toast, yoghurt or a banana before getting their gear organised and heading out.

"You don't need to eat anything before you go if you're exercising for less than an hour," says Turnbull.

What is important is to have breakfast within 20 to 30 minutes of getting back from the run and not waiting until mid-morning when you're settled in at work.

"Basically what happens is once you've finished training your body metabolically is absolutely pumping to be re-fuelled and it's very efficient at doing that. But once you go past that it takes a lot longer for you to get the same speed of recovery," Turnbull says. "It's very important for people exercising every day."

For those that, like me, prefer an evening run then a decent afternoon tea will help keep energy levels up.

Turnbull says a small bowl of cereal - she likes bircher muesli made up with grated apple and a dollop of yoghurt - or a one slice bread sandwich in the afternoon are options.

She says a "massive error" people make if they're running to keep weight off is to have something like a salad with tuna for lunch, an apple for afternoon tea, then try and run for an hour and a half.

"You've just not got enough carbohydrate in your body for you to run for that long."

It's likely that you'll "hit the wall", then come back so hungry you want to chow down on anything and everything and reach for a sports drink to get you through, she says.

Now, I had been wondering about sports drinks, carb gels and the like. Do I need them when I run?

Turnbull says sports drinks are incredibly helpful and get sugars and minerals to muscles very quickly, but there is a big trade-off - 15 teaspoons of sugar, or the same number of calories as a chocolate bar.

Have a sports drink after a relatively easy run and you end up glugging down more calories than you've burnt.

"If you're a pretty lean, fit person with a spot-on diet then using sports drinks every now and then is not the end of the world."

So, with nicely topped up glycogen stores and a decent snack beforehand it should be possible to run unaided for around 90 minutes.

"Once someone is going over the 90 minutes, two hour mark, that's where you're going to start needing to use sports drinks and gels because essentially you've used up everything you've eaten, you are starting to deplete your glycogen stores and you don't want to do that," Turnbull says.

Turnbull points me to a couple of booklets that give more food suggestions for fuelling my running and recovery.

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* Work up a thirst with a run through the vineyards of Marlborough in the St Clair Vineyard Half Marathon, Saturday May 14.

* Spend Mother's Day running 5km or 10km around the trails and paths of the old airbase at Hobsonville Point in the Runway Challenge, Sunday May 13.

What's your favourite pre- or post-run food?