Carb Loading and Race-Day Fuelling: A Female Athlete's Guide
You trained for months. Then you fuelled race day on a coffee, a banana and a prayer, and blew up at 30k. Let’s not do that again.
Race nutrition is where so many women come unstuck. Not because it is complicated, but because it never gets practised, and because a lot of women turn up to the start line already under-fuelled from weeks of eating too little.
This is the whole picture. What carb loading actually is, the numbers that matter, what to eat on race morning, and how to fuel during without wrecking your gut. It works for a marathon, a 70.3, an ultra, any endurance day over about 90 minutes.
Carb loading is not a magic weekend that rescues months of eating too little. It is the last layer on top of consistent, adequate daily fuelling.
If you have spent your training block chronically under-eating, your muscle glycogen stores, your hormones and your energy are already compromised. Fix the everyday fuelling first. Then carb loading actually does its job.
What Carb Loading Actually Is
Carb loading means topping up the carbohydrate stored in your muscles and liver, called glycogen, in the day or two before a long race. That stored glycogen is your premium fuel for endurance. More in the tank means you go further before you hit the wall.
It only matters for longer efforts. For anything under about 90 minutes, your normal stores are plenty and loading is pointless. For a marathon, a 70.3 or an ultra, it makes a real difference.
Sports nutrition guidance is fairly settled here.
- In the 36 to 48 hours before a long race, aim for roughly 10 to 12 grams of carbohydrate per kilogram of body weight per day.
- For a 65kg woman that is around 650 to 780g of carbs a day. It is more than it sounds.
- This is not “eat everything”. It is deliberately shifting your plate towards carbs and slightly down on fat and fibre.
- You do not need to hugely increase total calories. You are changing the balance, not gorging.
- Rice, pasta, potatoes, bread, oats, noodles as the centre of each meal.
- Fruit, juice, jam, honey and the odd sweet treat to top up easily.
- Go lighter on very high-fibre, very high-fat and very heavy foods, which sit in the gut.
- Keep protein moderate and steady. You do not need loads on these two days.
Two things trip women up. First, a giant heavy pasta feast the night before, so much that you sleep badly and start the race bloated. Second, adding loads of new high-fibre “healthy” food and spending race morning on the toilet.
Fix: spread the carbs across all your meals over two days, keep them familiar and lower-fibre, and do not make the night-before dinner enormous.
A fill-in template for your two-day load, race breakfast and hourly race fuel, in grams. The one I use with my athletes so nothing is left to chance on the day. PDF, straight to your inbox.
Send it →Race Morning
The goal of breakfast is to top up your liver glycogen, which drains overnight, without leaving you heavy or needing the loo at the wrong moment.
- Eat 1 to 4 grams of carbohydrate per kilogram of body weight, 1 to 4 hours before the start.
- In practice: the earlier you eat, the more you can have. Three hours out, a proper bowl of porridge with banana and honey plus a slice of toast. Ninety minutes out, something lighter.
- Keep it familiar, lower-fibre and lower-fat. Now is not the time for a giant fry-up or a brand-new food.
- Sip fluid with electrolytes. Do not arrive dehydrated, and do not overdrink either.
- A top-up 15 minutes before, a banana or a gel, is fine if you like it.
Some women train fasted and think they should race fasted too, or they are too nervous to eat. Racing a long event on empty is a recipe for bonking and a miserable back half. Nerves are not a reason to skip breakfast.
Fix: practise your exact race breakfast before long training sessions so it feels normal, and eat it on the day even if you are nervous.
Fuelling During the Race
This is the number most women undershoot. During a long race your body needs a steady drip of carbohydrate to keep the tank from emptying.
- Aim for roughly 60 to 90 grams of carbohydrate per hour for races over about two and a half hours.
- At the higher end, use products that blend glucose and fructose, which your gut absorbs more easily together.
- Start early. Take your first fuel in the first 30 to 45 minutes, not when you already feel empty. By then it is too late.
- Take it in regular small amounts, for example a bit every 20 minutes, rather than one big hit an hour.
- Drink to thirst and include electrolytes, especially in heat. Hello, Singapore.
Train Your Gut
Your gut is trainable, just like your legs. If you only ever practise fuelling on race day, expect trouble. This is one of the most common causes of race-day stomach disasters, and it is completely preventable. More on that in my guide to fuelling long runs without GI issues.
- Practise your exact race fuel on your long training sessions. Same gels, same drink, same timing.
- Build the amount up gradually over weeks so your gut learns to absorb 60 to 90g an hour comfortably.
- Find what your stomach tolerates now, well before race day. Some guts hate certain gels. Better to learn that in training.
- Rehearse your race breakfast before weekend long runs too.
Do Women Need to Carb Load Differently to Men?
This is a fair question, because most of the classic carb-loading research was done on men. The honest answer is that the same principles apply, but there is an important nuance for women.
The key is total energy. Women, on average, eat less overall and are more likely to be under-fuelled day to day. If you go into a loading phase already in an energy deficit, you cannot fill your glycogen stores properly no matter how much pasta is on the plate. So the real fix for a lot of women is not a clever loading trick. It is eating enough, consistently, in the weeks before, so that the load actually has somewhere to go. Get the everyday fuelling right and the loading works as it should.
The practical takeaway: hit the carb numbers, and make sure you are genuinely eating enough energy overall, not quietly restricting while trying to load. The two do not mix. One more nuance worth knowing: your cycle can affect how your body uses fuel, and some women feel they need a little more in the days before their period. It is one more reason to go by how you feel and eat enough, rather than following a rigid number to the gram.
A Worked Example: Marathon Weekend
Numbers are easier when you can see them on a timeline. Here is a simple version for a Sunday morning marathon, for a woman around 65kg. Adjust to your own weight and race.
- Normal balanced eating, maybe nudging carbs up a little. No need to go mad two days out.
- Hydrate normally across the day.
- Carbs as the centre of every meal and snack. Porridge and toast at breakfast, a big rice or pasta lunch, easy carb snacks through the day, a sensible pasta or rice dinner.
- Aim for the 10 to 12g per kg target, so roughly 650 to 780g of carbs across the day.
- Go lighter on very high-fibre and very high-fat foods so you are not heavy or caught short on race morning.
- Do not make dinner enormous. A normal-sized carb-rich meal beats a food coma.
- Three hours before the gun: porridge with banana and honey, a slice of toast, a coffee if that is your normal. Roughly 1 to 4g per kg.
- Sip fluid with electrolytes. Do not overdrink.
- Fifteen minutes before: a banana or a gel if you like a top-up.
- Then fuel from early in the race, 60 to 90g of carbs per hour.
What to Avoid in the 24 Hours Before
Race-day gut disasters are usually made the day before. A few simple avoids save a lot of misery.
New foods. Nothing you have not eaten before a long session. Race week is not the time to experiment.
A sudden pile of extra fibre. Big salads, lots of veg, beans and wholegrains right before a race can send you straight to the portaloo queue. Ease off fibre in the last day.
Very high-fat, very heavy meals. They sit in the gut and slow you down.
Too much alcohol. It disrupts sleep and hydration. Save the celebration for after.
Getting dehydrated, or overdrinking. Aim for pale-straw wee, not clear. Drinking litres of plain water can flush your electrolytes.
What About Caffeine?
Caffeine is one of the few supplements with genuinely strong evidence for endurance performance, and it is worth knowing how to use it if you tolerate it well.
A moderate dose, in the region of 3mg per kg of body weight, taken around 45 to 60 minutes before the start, can improve endurance performance and reduce how hard the effort feels.
For a 65kg woman that is roughly 200mg, about two strong coffees, or a caffeinated gel or two during the race.
More is not better. Too much brings jitters, a racing heart and gut trouble, which on race day is the last thing you want.
Practise it in training. If caffeine upsets your stomach or you are sensitive to it, race day is not the time to find out.
If you avoid caffeine or it does not agree with you, you are not missing out on much. It is a small edge, not a magic bullet.
Practice Is the Whole Point
If you take one thing from this, let it be this. Everything here, the load, the breakfast, the hourly carbs, the caffeine, has to be rehearsed in training so that race day is a repeat of something your body already knows. The women who fuel well on race day are not lucky. They practised. Your long weekend sessions are your dress rehearsals. Use them.
Everyday Carbs Are Not the Enemy
I have to say this because so many of the women I coach have spent years quietly afraid of carbs. Here is the truth. Carbohydrate is your body’s preferred fuel for endurance. It is not something to earn or feel guilty about. It is the thing that lets you train hard, recover well and hold your hormones steady.
Carb loading before a race only works if your everyday relationship with carbs is healthy in the first place. If you spend your whole training block avoiding rice, bread and pasta, then try to cram it all in the day before a race, your gut is not used to it and your glycogen stores were never full to begin with. Eat carbohydrate around your training all the time, not just before races. Race-day fuelling is the sharp end of an everyday habit, not a one-off event you white-knuckle through. If food feels loaded and stressful, that is worth working on with proper support, and it is exactly the kind of thing I help women with.
The Short Version
Carb loading only matters for races over about 90 minutes, and it sits on top of good everyday fuelling.
Load with 10 to 12g of carbs per kg of body weight per day for 36 to 48 hours, spread across meals, lower-fibre, not one giant feast.
Race breakfast: 1 to 4g per kg, 1 to 4 hours before, familiar and light on fibre and fat.
During the race: 60 to 90g of carbs per hour, started early and taken in small regular amounts, with electrolytes.
Train your gut in advance. Never trial anything new on race day.
Fuel the race you trained for. It is the difference between surviving the finish and racing it.
This article is general information, not personalised nutrition advice. Individual needs vary. If you have a medical condition affecting diet or digestion, work with a qualified professional.
- You have blown up or had gut trouble in a race and never quite worked out why
- You know you probably under-fuel but the fear of eating more keeps stopping you
- You want a proper race-day fuelling plan in actual grams, not vague advice
- You want it from a qualified sports nutritionist who coaches women
If you ticked two or more, this is exactly what my coaching covers.
Apply to work with me →If you want your race fuelling planned properly, practised and nailed down, that is what I do.
Female-specific coaching from a qualified Nutritionist and Fertility Nutrition Specialist. Training and nutrition in one place, built on awareness, not restriction.
The application takes two minutes. I read every one myself. I will WhatsApp you within 24 hours on weekdays.
Apply to work with me →Frankie x