Carb loading is how cyclists top off muscle glycogen before a long event so the tank lasts to the finish. This guide covers exactly how many carbs you need, a day-by-day race-week protocol, the best foods to eat, and the mistakes that sabotage the whole effort. Done right, it can delay fatigue and protect your pace over any ride longer than about 90 minutes.
What Carb Loading Actually Does
Your muscles and liver store carbohydrate as glycogen, and that glycogen is the fuel your legs reach for first at race pace. A typical rider holds roughly 400–500 grams of it — enough for 90 to 120 minutes of hard riding before stores run low and your power sags. Carb loading exploits a process called glycogen supercompensation: when you flood the body with carbohydrate while training volume drops, the muscles pack in up to 50% more glycogen than normal.
That extra reserve buys you time. It does not make you faster in the first hour, but it pushes back the moment when fatigue forces you to slow down — the same wall you hit when you run out of glycogen and bonk on a long ride. For events where the finish is decided in the final hour, a fully loaded set of legs is a genuine advantage.
Who Needs to Carb Load (and Who Doesn’t)
Carb loading only pays off when the event is long enough to deplete your glycogen stores. Use this as a rule of thumb:
- Worth it: continuous efforts longer than about 90 minutes — a gran fondo, a century, a road race, a long gravel event, or a hard group ride of two hours or more.
- Not worth it: a 40-minute criterium, a short time trial, or an easy recovery spin. You will not come close to emptying your tank, so the extra fuel just adds weight.
- Borderline: a 60–90 minute hard effort. A single high-carb day beforehand is plenty; a full multi-day load is overkill.
If you are building toward a big day on the calendar, pair your loading with a proper training taper. Cutting volume in the final days is what gives the muscles the chance to stockpile glycogen instead of burning it in training.
How Many Carbs You Actually Need
Forget vague advice like “eat more pasta.” The research-backed target is measured per kilogram of body weight:
- 10–12 grams of carbohydrate per kilogram of body weight, per day, for the 36–48 hours before your event.
- A 70 kg rider therefore targets 700–840 g of carbs per day.
- A 60 kg rider targets 600–720 g per day; an 85 kg rider targets 850–1,020 g per day.
Those numbers are higher than most riders expect, and that is the point — undershooting is the single most common reason carb loading fails. To hit them without feeling stuffed, lean on carb-dense, low-bulk foods and spread intake across every meal and snack. The modern protocol has also dropped the old “depletion phase,” where riders used to ride themselves empty and eat almost no carbs for three days first. It made people miserable and research shows it offers no extra benefit. Just taper the riding and raise the carbs.
The Race-Week Carb Loading Protocol
Here is how the final days should look for an event on Sunday. Adjust the day names to your own race date.
Thursday & Friday (2–3 days out): normal eating, easy riding
Keep carbohydrate at your usual level and ride easy and short. This is the taper window: low intensity, low volume. You are not loading yet — you are simply keeping glycogen from being burned off.
Saturday (1–2 days out): the loading window begins
Start hitting your 10–12 g/kg target. Eat five or six carb-focused meals and snacks rather than three giant plates. Cut back on fat and fibre (more on that below) and keep protein moderate. Drink to thirst — glycogen binds water, so you need extra fluid to store it.
Sunday morning (race day): top off the tank
Eat a carb-rich breakfast of 1–4 g of carb per kg of body weight, 1 to 4 hours before the start. A practical version for a 70 kg rider is roughly 140 g of carbs (around 2 g/kg) about three hours out — oatmeal with banana and honey, a bagel with jam, or rice with a little salt. Keep it low in fat and fibre so it clears your stomach in time, and sip water or a sports drink up to the gun.
What to Eat: Practical Food Choices
The best loading foods are high in carbohydrate but low in fibre, fat, and bulk, so you can eat enough without feeling like you swallowed a brick. Reliable staples include:
- White rice, white pasta, and white bread (lower fibre than wholegrain versions on race week)
- Potatoes, boiled or mashed without heavy butter
- Bananas, ripe fruit, and fruit juice
- Oats, cereal, pancakes, and bagels
- Honey, jam, maple syrup, and dried fruit for easy concentrated carbs
- Sports drinks, which deliver carbs and fluid at the same time
A sample loading day for a 70 kg rider might be: large bowl of oats with banana and honey for breakfast; a bagel with jam mid-morning; white rice with a modest portion of chicken for lunch; a sports drink and dried fruit in the afternoon; pasta with a light tomato sauce for dinner; and a bowl of cereal before bed. That stacks up to roughly 700 g of carbohydrate across the day without any single meal being overwhelming.
If your gut struggles to handle big carbohydrate volumes, it is worth practising gut training to improve how much carbohydrate you can absorb in the weeks before your event. A trained gut tolerates both the loading days and the high in-ride intake that follows.
Common Carb Loading Mistakes
- Eating too much fat and protein. Loading up on cheesy, oily, or meat-heavy meals fills you up before you hit your carb target. Keep fat and protein modest and let carbs lead.
- Too much fibre. Wholegrains, beans, and big salads are healthy day to day but cause bloating and urgent bathroom stops on race morning. Switch to lower-fibre white carbs for the final 24–36 hours.
- Trying new foods. Race week is not the time to experiment. Rehearse your loading menu during a training block so you know your gut tolerates it.
- Panicking about the scale. Expect to gain 1–2 kg. That is water stored alongside glycogen (about 3 g of water per gram of glycogen), not fat, and it is a sign loading worked.
- Under-eating from nerves. Appetite often drops before a big event. Plan your meals and snacks in advance and eat on schedule rather than on hunger.
Don’t Stop Fuelling on the Bike
Carb loading fills the tank, but it does not replace fuelling during the event. Even fully loaded, you will deplete glycogen on anything beyond two hours, so keep taking on 60–90 g of carbohydrate per hour once you are riding, using gels, drink mix, chews, or real food. Pair that with your hydration and electrolyte strategy to keep absorption and cramping in check.
Think of the days before the event as building the reserve and the ride itself as topping it up. The two together — a loaded start plus steady in-ride carbs — are what carry strong legs all the way to the line. If you are new to events, fold this into your wider plan for preparing for a gran fondo so nutrition, taper, and pacing all line up on the day.
Carb Loading vs. Everyday Carb Periodization
Carb loading can seem to contradict the “train low” advice you may have read, where riders deliberately do some easy sessions with low glycogen to boost fat-burning adaptations. Both are valid — they just serve different jobs. Day to day, many cyclists match their carbohydrate intake to the demands of each session, eating less on easy days and more around hard ones. That ongoing strategy is carbohydrate periodization, and it is about long-term adaptation.
Carb loading is the opposite move made deliberately, for a short window: when a key event arrives, adaptation stops mattering and raw fuel availability becomes everything. You set the “train low” work aside, fill the tank completely, and race. The skill is knowing which phase you are in — build fitness with periodized carbs through the season, then switch to full loading in the final 48 hours before the events that count.
Carb Loading FAQs
Will carb loading make me slower from the extra weight?
You will gain around 1–2 kg, almost all of it water bound to the stored glycogen. For any event longer than 90 minutes, the performance benefit of full glycogen stores far outweighs the tiny cost of that water weight. For a short, climb-heavy effort under an hour, the maths tips the other way — which is exactly why loading is for long events only.
How far in advance should I start?
For most riders, 24–48 hours of high-carb eating is enough to supercompensate glycogen stores, provided training volume is low in that window. Starting a full week out is unnecessary and usually just leads to unwanted fat gain.
What if I have a sensitive stomach?
Prioritise low-fibre carbs (white rice, white bread, bananas, sports drinks), spread intake into smaller frequent portions, and rehearse the exact menu during training so there are no surprises. Liquid carbs such as sports drinks and juice are often easier to tolerate in volume than solid food.
Can I carb load on a low-carb or keto diet?
You can, but a fat-adapted rider’s muscles are less practised at storing and rapidly using glycogen, so reintroducing large carb volumes right before a race can cause gut distress. If you follow a low-carb approach in training but plan to race long, trial a carb reintroduction well before your event rather than loading cold.
The Bottom Line
For any ride longer than about 90 minutes, carb loading is one of the simplest performance gains available: aim for 10–12 g of carbohydrate per kilogram of body weight per day across the 36–48 hours before your event, lean on low-fibre and low-fat carb sources, taper your training, and top off with a carb-rich breakfast on race morning. Rehearse it before a key day, keep fuelling once the ride starts, and your legs will still have something left when it matters most.
