Carb loading before a big race? Here’s how to do it!

Written by Martin Ebner,
Last updated October 2026

Carb loading sounds magnificent. After weeks of training, science appears to hand you a bowl of pasta and tell you to get involved.

Unfortunately, Michael Scott’s fettuccine Alfredo strategy remains a terrible plan. Carb loading isn’t one enormous dinner before a race. It’s a planned increase in carbohydrate, combined with less training, so you arrive at the start with as much stored fuel as your body can sensibly hold.

I haven’t personally carb loaded for a marathon, so I’m not going to invent a secret race-week ritual. The useful answer comes from sports-nutrition research, and it’s reassuringly simple. Eat enough, spread it out and stop before race preparation becomes an endurance event of its own.

WHAT CARB LOADING IS FOR

Your muscles and liver store carbohydrate as glycogen. During prolonged exercise, that glycogen helps you maintain the pace you’ve trained for. Fat contributes energy too, but it can’t replace carbohydrate quickly enough when the intensity rises and you’re trying to perform rather than merely survive.

Carb loading aims to maximise those glycogen stores before a long event. It’s most useful for exercise lasting longer than about 90 minutes, including marathons, long-distance cycling, triathlons and similar endurance events. Research on marathon nutrition supports combining a training taper with a high-carbohydrate intake during the final 36 to 48 hours.

A 5K, an ordinary gym session or an hour-long cycle doesn’t require two days of industrial pasta consumption. You already carry enough glycogen for shorter sessions if you’ve been eating normally.

THERE IS A LIMIT

The formal carb-loading recommendation for a long endurance event is around 10 to 12 grams of carbohydrate per kilogram of bodyweight each day during the final 36 to 48 hours.

For someone weighing 70 kg, that’s 700 to 840 grams of carbohydrate per day. It’s a serious amount of food. Reaching it usually requires several meals and snacks, with some lower-fibre foods and drinks that don’t leave you feeling permanently stuffed.

It isn’t a competition to see who can eat the most. In a small carb-loading study, eight endurance-trained men reached their highest measured muscle-glycogen level after one day of rest and 10 grams of carbohydrate per kilogram. Another two days at the same intake didn’t push it higher.

That doesn’t prove everybody’s glycogen stores will be full after exactly 24 hours. It does confirm the basic point: storage is finite. Once your muscles are full, another mountain of food is more likely to test your digestion than improve your race.

START 36 TO 48 HOURS BEFORE THE RACE

The old approach involved a punishing workout and several low-carbohydrate days before loading. You don’t need to make race week that complicated.

Reduce your training volume, rest properly and increase carbohydrate during the final day or two. Spreading the food across 36 to 48 hours is usually more comfortable than trying to force everything down in one day.

Reducing your workload matters. If you keep depleting glycogen while trying to replenish it, you’re pressing the accelerator and brake together. This is one occasion when rest and recovery are part of the performance plan.

CHOOSE CARBS YOUR STOMACH ALREADY KNOWS

Race week isn’t the time to discover an exotic new grain, triple your vegetable intake or accept a nutritional challenge from somebody on Instagram.

Choose familiar carbohydrate-rich foods that you know you digest well. Rice, pasta, bread, bagels, potatoes, cereal, pancakes, bananas, fruit juice, rice pudding, pretzels and sports drinks can all help.

Normally, I’m in favour of fibre. Immediately before a long race, enormous portions of beans, bran cereal, raw vegetables and seeded bread may be less helpful. Temporarily choosing lower-fibre foods can make the carbohydrate target easier to reach and reduce the chance of your digestive system becoming the main event.

The same applies to fat. Fat is part of a healthy diet, but it slows digestion and takes up room when carbohydrate is the priority. Keep protein at a normal level, reduce unnecessary fat and let carbohydrate do most of the extra work.

This is one of the rare occasions when white bread may be more useful than the worthy seeded loaf staring at you from the cupboard.

A PRACTICAL CARB-LOADING DAY

The exact portions depend on your bodyweight, appetite and carbohydrate target. This is the shape of a sensible day, not a fixed meal plan that everybody must follow.

Breakfast: Low-fibre cereal with milk or yogurt, toast with jam or honey, a banana and fruit juice.

Mid-morning: A bagel with jam, rice pudding or a cereal bar, with water or a sports drink.

Lunch: White rice or pasta with a modest serving of lean protein, a simple sauce and some bread.

Afternoon: Pancakes with honey, pretzels, toast, a smoothie or another familiar carbohydrate-rich snack.

Dinner: Rice, pasta or potatoes with lean protein and a meal you already know sits well.

Later, if required: Cereal, toast, rice pudding or a carbohydrate drink can help without forcing another full meal.

You don’t need to eat nothing but beige food for two days, but beige is going to put in a strong performance.

DON’T SAVE EVERYTHING FOR THE NIGHT BEFORE

A huge dinner won’t compensate for barely eating all day. It may leave you bloated, thirsty and unable to sleep, which is a poor exchange for a few more forkfuls of pasta.

Distribute carbohydrate across the day and eat dinner at a normal time. The goal is to begin the race feeling fuelled and comfortable, not like you’re still digesting the restaurant.

Avoid experimenting with unfamiliar supplements, rich sauces, enormous portions or foods that have caused problems during training. A family-sized lasagne isn’t a carb-loading protocol.

WHAT TO EAT ON RACE MORNING

The general recommendation is 1 to 4 grams of carbohydrate per kilogram of bodyweight during the 1 to 4 hours before exercise. The sports-nutrition position paper behind that range leaves room for timing, appetite and individual tolerance.

If you’re eating four hours before the start, you can manage a larger meal. If you’ve only got an hour, stay near the lower end and choose something easy to digest.

Toast with jam, a bagel, cereal, porridge, pancakes, a banana, juice or a sports drink can all work. The best option is the one you’ve already tested before a long training session.

Race morning should feel familiar. If breakfast suddenly resembles a food experiment, you’ve left the planning too late.

CARB LOADING DOESN’T FUEL THE ENTIRE RACE

Starting with full glycogen stores helps, but it doesn’t remove the need to eat during a long event.

Current endurance carbohydrate guidance recommends roughly 30 to 60 grams of carbohydrate per hour during prolonged exercise. Events lasting more than about two and a half hours may benefit from intakes approaching 90 grams per hour, generally using a combination of carbohydrates such as glucose and fructose.

Don’t hear “up to 90 grams” and attempt it for the first time on race day. Higher intakes need practice. Gels, drinks, chews or ordinary food can all work, but your digestive system needs to be involved in the training plan too.

EXPECT THE SCALES TO MOVE

You may weigh a little more after carb loading. That doesn’t mean you’ve suddenly gained body fat.

Stored glycogen is associated with additional water inside the muscle. Research examining glycogen and body water places that water storage at several grams for each gram of glycogen, although the exact relationship varies.

That extra weight is part of arriving properly fuelled. This isn’t the moment to panic, slash your food or try to sweat it out before the start.

PRACTISE THE PLAN BEFORE RACE WEEK

Use one or two long training sessions to test your pre-race meal and the carbohydrates you intend to consume during the event.

Pay attention to energy, hunger, bloating, bathroom urgency and how easy it is to keep eating once you’re tired. A systematic review of gut training found that repeated carbohydrate feeding during endurance training may improve tolerance and reduce digestive discomfort.

Your legs need training, but so does your stomach. The finish line is a terrible place to discover that your chosen gel disagrees with you.

FUEL THE RACE, NOT YOUR NERVES

Carb loading works when the event is long enough, the amount is appropriate and the food agrees with you. It doesn’t require a week of deprivation, one ridiculous meal or eating until you feel ill.

Start 36 to 48 hours before the race, reduce your training, spread carbohydrate across familiar meals and stop treating more as automatically better. Arrive fuelled, comfortable and ready to use all the work you’ve already done.

Once you cross the finish line, post-workout nutrition will help you begin the recovery process.

If you’ve ever wondered whether a second bowl of pasta is sports nutrition or simply optimism with parmesan, Check It Oot is where I separate useful fitness advice from the nonsense. One email once or twice a month, written by me and delivered straight to your inbox.