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Cycling nutrition: A quick guide to carb loading

Chris Saunders
24 Nov 2017

Got a big ride on the horizon? Here's how to stock up on energy the tried and trusted way

First things first, what exactly are carbs? Carbohydrates are sugar-based molecules which the body can convert into glucose.

This glucose is then stockpiled in the liver and muscles as glycogen – ie molecules that serve as a long-term energy store, which can be tapped into during a gruelling ride.

The liver can hold about 100g of glycogen from carbs (which equates to about 400 calories of energy) while your muscle mass can store as much as three times that.

Typically carbs are found in naturally occurring wholefoods like oats, brown rice, sweet potatoes, regular potatoes, beans and lentils.

So what exactly is carb loading?

Carb (or sometimes carbo) loading is simply the term used to describe stuffing your diet full of carbohydrates in order to maximise the glycogen stores in your muscles and liver.

Devised in the 1960s, the technique works off the theory that with more glycogen available, the longer you’ll be able to exercise before fatigue sets in.

So what’s the science behind it?

In its original incarnation the carb-loading technique consisted of a two-part programme that was carried out a full week before a race.

It started with a regime of three days of heavy exercise coupled with a low-carb diet to strip the body of its existing glycogen stores.

Then three days before the race, riders would do the exact opposite – stop exercising altogether while flooding their bodies with carbs.

The theory was that by clearing out the body’s energy stories in this way, you could essentially trick it into storing much more energy than it would normally do once the glycogen tap was turned back on.

However, scientists soon realised that this regimen had a number of drawbacks. Not only did it interfere with exercise tapering – the now universally accepted practice of gradually reducing the amount of effort put into training in the run-up to a big event – but resulted in more worrying side-effects.

Cyclists complained of feeling weak, irritable and tired while many failed to achieve high glycogen levels even after three days of having nothing but carbs poured back into their bodies.

These days it’s now accepted that the first part of the programme – the carb-depletion phase – is pure folly.

A period of carb-loading two to three days prior to an event (combined with a tapered exercise regime) meanwhile, is now considered the best way to prepare for any race that lasts longer than 75 minutes.

So will carb-loading make me faster?

By filling your muscles to the brim with glycogen you should be able to ride for longer, and that means avoiding the dreaded bonk.

The bonk – or hitting the wall – happens when you run out of glycogen during a ride and your body slows down as it starts to rely on stored fat for its energy.

Studies have shown that carb-loading increases time to exhaustion by about 20%, while improvements in performance hover at around 2%.

So its real benefit is in helping you to actually rack up the miles in the first place, rather than in how quickly you ride them, particularly when that ride is longer than 75 minutes.

Are there any other benefits?

According to studies conducted at the Human Performance laboratory at the University of Birmingham, carb-loading isn’t just for racing – it also allows you to train harder, as well as reducing symptoms of overtraining (which include chronic fatigue, depression, headaches and irritability) as well as preventing reductions in immune functionality.

How and when should I carb-load before an event?

To maximise glycogen stores in your body two or three days prior to an event, ensure that you consume approximately 10g of carbs per kilo of bodyweight per day.

So for example, a cyclist who weighs 70kg would need to consume around 700g of carbs each day leading up to an event to benefit properly.

Each gram of carbs contains around four calories, which equates to 2,800kcal per day during the carb-loading phase.

A 70kg rider would typically burn around 850kcal an hour during a moderately paced ride so it’s easy to see how carb-loading can help.

So I should basically live off of pasta, then?

You’ll be eating a lot of carbs so you want to try to eat them little and often rather than just piling your plate high with them during regular mealtimes.

Eating five or six smaller meals is a much more digestible way of getting them into your system and it won’t leave you feeling queasy or knackered.

You also need to make sure you’re not radically increasing the amount of calories you consume, instead focus on the form in which you consume them.

Carb-loading isn’t about eating more, it’s about eating more carbs.

And as good as a bowl of spaghetti is, there are plenty other ways of getting carbs into your diet.

Rice, oatmeal, and yoghurt are all easily digested options. Many fruits are high in carbs but are also high in fibre, and because fibre takes longer to digest, come race day it can cause tummy troubles, especially with the added stress of nerves.

With fruit, stick to low-fibre options such as bananas. If you go for apples, peaches or pears, peel them first to reduce the fibre.

The same goes for vegetables such as baked or sweet potatoes. A typical meal plan might include a bowl of porridge oats and a banana for breakfast, grilled salmon with skinned sweet baked potato and dark green leafy veg for lunch, and tofu or chicken sir fry with veg and wholegrain rice for dinner.

Snacks in between and when you’re on the ride itself could consist of anything from a handful of dried fruit, a banana to an energy bar, drink or gel – just make sure it’s food your body is used to.

Any other advice?

If you think about it, eating both before and immediately after an event is actually part of the ride, so while you should be looking for healthy options, make sure you’re not stuffing your face with foods you detest just because you think it’ll produce optimal results.

After all, this whole cycling lark is supposed to be fun, remember!

10 top carbs

Be sure to include this little lot on your shopping list…

Tubers No, not the brass instrument – we mean potatoes, sweet potatoes, yams and the like, But not in the form of French fries or crisps, OK?

Legumes Lentils, chickpeas, beans etc all pack in the calories without threatening to chub up your tum. In fact, studies have shown that they can actually aid weight loss.

Brown rice White rice has a greater shelf life thanks to the milling it undergoes, but that process also strips it of vital nutrients.

Wholegrain pasta/bread Wholegrain products (see above) are significantly higher in fibre and nutrients than their refined counterparts.

Oats Among other things they contain a super-fibre called beta-glucan that’s great at battering high cholesterol.

Blueberries And for an extra blast of carbs why not smother your breakfast oats in blueberries? They’re crammed with antioxidants, too!

Bananas These are stuffed with carbs (30g in one large banana alone) plus a healthy hit of potassium, which is good for keeping blood pressure down.

Chestnuts All nuts rock but chestnuts have almost zero protein or fat compared to other nuts.

Barley It’ll fill you up with a soluble fibre source that’s been linked with lower cholesterol and decreased blood sugar levels. Add it to salads, risottos, casseroles, and soups.

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