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Runners' top diet blunders – and how to avoid them

Whether you're training for your first 5K race or your umpteenth half-marathon, or if you're simply wanting to shed that winter weight, it's important to develop an eating strategy that will help you run your best.

Poor eating habits – even seemingly small mistakes – can sabotage your running and undermine your diet, too. To get into peak running form, it's important to watch for – and avoid – these common diet blunders.

Running on empty

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Muscle glycogen (carbohydrate) stores are crucial to running performance, especially in half and full marathons. The only way to fill your glycogen stores is to eat carbohydrate-rich foods like whole grain breads and cereals, pasta, brown rice, sweet potato, legumes, fruits and low fat dairy products each day.

If your typical weekday scenario is one of haphazard eating – e.g. you skip breakfast and/or lunch and miss snacks – your muscles won't get the fuel they need for exercise.

An everyday diet for runners should sustain energy and blood sugar (glucose) levels all day long. That means eating three balanced meals with a mix of carbohydrate, protein and fat, and two small snacks.

Skipping the pre-run snack

Plan your snacks around your runs to ward off hunger and prevent early fatigue caused by your blood sugar dropping too low. If you run at lunch, you'll need a late morning snack one or two hours before you head out the door. If you run after work, a late afternoon snack is in order.

Pre-run carbohydrate-rich snacks include fig bars, whole grain cereal bars, dried fruit, yogurt and berries, smoothies and energy bars (look for energy bars made with whole foods like fruit, nuts and oats).

If you're a morning runner, your distance will determine whether you need a snack. If you're running for less than an hour, you don't need any pre-workout fuel. But if you don't like to run on an empty stomach, eat something small like a banana or yogurt.

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For longer runs, eat a snack that's easy to digest. Try fruit and yogurt, a fruit smoothie, toast with jam, or a small bowl of low-fibre cereal with milk (no more than 2 grams fibre per serving).

Drinking too little

Being properly hydrated is essential to peak running performance. If you don't drink much during the day – except your morning coffee – you're more likely to fatigue early during your run.

Drink water during the day even if you don't feel thirsty. Runners should consume at least 9 to 12 cups (2.2 to 3 litres) of fluid each day. During a run, drink 125 to 175 ml of water every 10 to 15 minutes.

For runs longer than one hour, hydrate with a sports drink, which replenishes water, electrolytes lost through sweat and carbohydrates burned by your muscles.

Justifying extra calories

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It's so easy to do – turn a blind eye to a cookie here or an extra helping there because you're running four days a week. Surely you're burning those calories off. So why isn't the needle on the bathroom scale budging?

If you've taken up running to shed a few pounds, justifying a few extra calories each day will only help you hold your weight steady. Truth is, running by itself won't help you lose much weight. To drop excess pounds, you need to combine running with a lower calorie diet.

Skimping on calories

Cutting a few hundred calories every day can help runners trim down. But cutting too many calories and increasing your mileage simultaneously is counterproductive.

If you deprive your body of the calories it needs to fuel normal bodily functions and exercise, it will break down muscle for fuel. The result: Weight loss will slow or come to a halt. What's more, your running performance will suffer.

Active women wanting to lose weight should consume no fewer than 1,400 to 1,600 calories per day; active men not less than 1,800 to 2,000 calories per day.

Overloading on carbs the night before

To boost muscle glycogen stores, runners "carbohydrate load" before a long run. But a huge pasta feast the night before can leave you feeling bloated during your run. Not to mention prompt the need for frequent bathroom stops.

To load your muscles with carbs effectively, moderately increase your intake of foods like pasta, rice, oatmeal, whole grains, sweet potato and fruit for three days before the long run. Super-sized portions the night before aren't necessary.

Don't wait for the big event to increase carbohydrates. Practice this before each long training run.

Not fuelling long runs

If you're gearing up for a half or full marathon, you need to consume carbohydrates during your long runs to help maintain your blood sugar level at a time when muscle glycogen stores are dwindling.

If you neglect to do so, you're more likely to "hit the wall"; you'll no longer have enough glucose in your blood and brain to function properly.

For runs longer than 75 minutes, consume 30 to 60 grams of carbohydrate per hour of running using a combination of sports drinks, energy bars, dried fruit, gummy bears or energy gels.

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