Running is about self-improvement, not Spartan self-denial. As performance coach Kim Ingleby (energisedperformance.com) says, "You need a balance: training, recovery, food and fun." So while runners might idolise the original marathon runner Pheidippides, we could just as easily take another tip from Ancient Greece. Enjoy "everything in moderation; nothing to excess".
BAD GUY: CARBS
The good news: Forget carb-counting. Cutting out pasta might shed a little superficial weight, but thrice-weekly 30-minute runs melt a pound of fat each month. "Complex carbs are vital for energy and recovery," says Ingleby. "Have a carb-rich snack like a banana immediately after running, to refuel glycogen stores."
In practice: Think of your plate as a clock face. Dedicate 35 minutes to carbs. Add 15 minutes of protein and healthy fats. The remaining 10 minutes? Have fruit for dessert.
BAD GUY: SALT
The good news: It's always wise to keep your salt intake below 6g a day. Yet during long runs "prolonged sweating can lead to low blood sodium levels," says Ingleby. "This makes it difficult to regulate the nervous system." That's why energy drinks contain sodium. Stay hydrated, and give the shaker a miss - but don't obsess about salt.
In practice: Beans on toast is high in sodium, but also contains a sixth of your daily magnesium and nine per cent of potassium RDA, vital electrolytes that strengthen bones and help prevent cramp.
BAD GUY: ALCOHOL
The good news: Moderate drinking (one to two units a day) is linked to lower risk of heart disease in those in their forties and above, and now the American Journal of Health Promotion reports that drinkers do up to 20 minutes more exercise than teetotallers on average each week.
In practice: Go for heart-healthy red wine, or beer, whose silicon content boosts bones.
BAD GUY: TV
The good news: What the 'idiot box' takes away, running can give back. In a study by The American College of Sports Medicine, students were given memory tests before and after exercise, and running improved mental performance.
In practice: Think of TV time as hour-long 'blocks', each a reward for meeting training goals.
This article was taken from our January 2010 issue (available on the newsstand now). Also in the January issue: 24 expert moves to get you fitter and faster from UK Olympian Jo Pavey, 8 ways to improve your nutrition without dieting, our expert guide to self-diagnosing foot pain and how to find your perfect pace.