I've been lucky to escape some of the British winter and spend three weeks down under! I'm back in shorts and singlet, running early in the morning to miss the heat of the day and have also taken part in two parkruns - one in Hamilton, New Zealand and one in Melbourne, Australia.

It can be a tricky balancing act to get the intake of energy and energy expenditure equation right. Just how do you go about working it out? Is it trial and error? Is there a mathematical formula? Surely it's not as simple as putting fuel in and then burning it up?