Distance runners have a thing against excess body fat. It slows you down by increasing the amount of energy the body needs to run, research shows.

But you can’t run without your muscles burning some fat as fuel, so how important is fat for running a marathon?

Professor John Hawley, exercise physiologist and head of the Exercise Metabolism Group at RMIT University, Melbourne, says about half the energy used during a four-hour run – about the average marathon time for a recreational runner – comes from fat.

That’s roughly 2600 kcals for a 70-75kg person.

Cutting the fat
“During the past decade researchers have been trying to find nutritional and training strategies to help athletes’ burn more fat,” says Prof Hawley.

“This is because the carbohydrate stores in the body are pretty small, and certainly not enough to get you though a marathon.”

And so, many top athletes world-wide have attempted all sorts of strategies to boost fatty acid levels before distance events, such as eating high fat-low carb diets seven to 14 days before a race, or even eating high fat meals on race-day.

Supersize me
But Prof Hawley’s latest research found that loading up on fat-packed foods pre-race could be pointless.

While Prof Hawley research is ongoing, he doesn’t recommend recreational runners log high mileage with low glycogen stores without professional guidance.

Making sure to consume both carbohydrate and fat in your diet will be useful for long training runs and races such as marathons.