Even if you don’t ascribe to the notion that all carbs are the devil’s work and must be strictly shunned at all times (and you shouldn’t), most people know that going overboard on pasta, rice, bread and the like can result in gaining weight, and try to keep their intake within reason.
That is except for the glorious, free-for-all nights that come before a big endurance event. Be it a marathon, a 150km cycle or a 1,000km kayak, you’re going to need to stock up on energy (especially for the 1,000km kayak) and that means going carb crazy.
It’s a free hit. The following day, you’re going to burn it off anyway, so hit the local Italian restaurant, order three or four of your favourite dishes and enjoy your carb-fest. All bets are off. There are no rules.
Except there are always rules. Five rules, to be exact.
- Save carb-loading for activities that are going to last 90 minutes and over.
- Don’t carb-load on the morning of the event. You should build up your carb intake over two to three days before the race.
- Don’t binge on fibre-rich carbs (pulses, brown rice, veg) the night before the event, especially if you’re not used to eating lots of fibre. It may – probably will – lead to stomach issues.
- It’s not a case of stuffing as much as you possibly can down your gob. Too much food will leave you feeling sluggish. A 70kg person should aim for around 2,800 calories of carbs in each of the final two days before an event.
- You should still eat balanced meals with protein and vegetables, rather than just platefuls of pasta. Staying healthy is as important as stocking up on glycogen.
That’s the advice from Dr Ieva Alaunyte, senior nutrition scientist at Lucozade Sport (opens in new tab). Keep reading for more information from Alaunyte, along with advice from Lisa Scheeper, nutritionist at Fresh Fitness Food (opens in new tab).
Why do you need to carb-load before a long run?
First off, it’s useful to know the reason for cramming in the carbs pre-run.
“Carbohydrates are muscle fuel – the body converts them to glycogen,” says Alaunyte. “We store glycogen in our muscles and it is converted back to glucose when we need it, for example when we walk, jog and run.”
“The longer and harder you train, the more carbohydrate you need to fuel your muscles. That’s why ensuring that you start your long runs with fully stocked carbohydrate stores is important.”
How long does a run need to be to require carb-loading?
Unfortunately, there’s no value to carb-loading before your Saturday morning parkrun, unless you really do take that 5K at an exceptionally slow pace.
“During a long training run – 60 to 90 minutes or longer – your glycogen stores will be depleted,” says Alaunyte.
“As a result, you might find running harder and your muscles may start to get fatigued. So if you are preparing for an event lasting longer than 90 minutes, such as a marathon, a long-distance cycling race or a triathlon, you are likely to benefit from carbohydrate loading.”
What happens if your glycogen stores run out?
Bad things happen, that’s what.
“The moment when glycogen runs out is the moment that runners ‘hit the wall’,” says Scheeper. “Beyond this point, you can still use the fat metabolic pathway to produce energy, but this is about 15% less efficient and you’ll inevitably slow down.”
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When should you carb-load? The evening before, the morning of the run, or both?
Clearly it’s not advisable to do your carb-loading on the start line of your marathon, or that fettuccine Alfredo is going to come right back up at mile three. As with almost everything, timing is important.
“A frequent mistake made by runners is eating an extra large dinner the night before,” says Scheeper. “The problem with this is that it doesn’t give your body enough time to digest it all and you’ll still feel bloated in the morning. On top of that, you can’t completely fill your muscles with glycogen from just one meal.
“For this reason, it’s better to start three days before your race. Since you’re tapering and running very few miles over these final days, the glycogen will accumulate in your muscles.
Aim to keep your total calorie intake for the day in line with your normal intake, but swap fats for more carbs. Try to get around 70% of your intake from carbs. Go for healthy unprocessed foods and leave the junk food out.
“The night before the race, enjoy a normal-sized but carb-heavy meal. Don’t eat too late and give your body enough time to digest it. You don’t want to wake up on race day full from the night before – it’s better to wake up hungry. And schedule your breakfast three hours before the start of the race.”
Should you avoid high-fibre carbs to keep your gut happy?
An unpleasant topic, but a vital one. A nasty case of runner’s trots is really going to take the shine off your marathon.
“Dietary fibre is important for a healthy balanced diet, so including it in your main meals is essential,” says Alaunyte. We sense a “however” on the horizon.
“However, for a meal or a snack before long runs, some runners prefer carbohydrate-rich foods and drinks that are lower in dietary fibre and fat because these can cause gut discomfort.
“Eating smaller but more frequent meals and snacks may also be beneficial. Essentially, while you do need to include fibre in your diet generally, you can reduce it for the meals and snacks leading up to your runs.”
Is there such a thing as too much carbohydrate before race day?
The biggest question of all: do you have to curtail your expansive carb feast in any way? Of course you do. Deep down, you already knew this.
“It is possible to eat too much carbohydrate, just as it is with any other nutrient like fat or protein,” says Alaunyte.
“Following a carb-loading plan is not as easy as it seems – it is not just as simple as ‘eat as much as you want of everything’. It is important to keep following a balanced diet leading up to a long-distance event.”
It’s also important to remember the point of carb-loading is to stock up on glycogen, and there’s a limit to how much your body can actually store. That means going above and beyond with carbs won’t help performance – and it could cause some gut unpleasantness.
The good news, however, is that the limit is a lot of carbs. For a 70kg person, we’re talking around 2,800 calories of carbs per day in the final couple of days before a big run. It’s better to break this up into several smaller meals, mainly because trying to eat that much in one sitting is no easy feat. Let the wild carb binge commence!
Won’t carb-loading lead to weight gain just before the race?
“It’s normal to gain some weight over this period but there’s no need to get worried about this,” says Scheeper. “For every gram of glycogen, your body stores around 2.6 grams of water too. This extra weight isn’t going to slow you down and it can be helpful in keeping you hydrated during the race.”
Lucozade Sport is the on-course drink at the Virgin Money London Marathon. Lucozade Sport is aiming to get one million people moving more by 2020 with the Made To Move Campaign. For information on how to win £1,000 towards your chosen charity visit lucozadesport.com/madetomove (opens in new tab)
Nick Harris-Fry is a journalist who has been covering health and fitness since 2015. Nick is an avid runner, covering 70-110km a week, which gives him ample opportunity to test a wide range of running shoes and running gear. He is also the chief tester for fitness trackers and running watches, treadmills and exercise bikes, and workout headphones.
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