Carb Loading for Triathlon: The 48-Hour Plan With Meals

Quick answer: Carb loading for triathlon means eating 8 to 12 grams of carbohydrate per kilogram of body weight per day for the 48 hours before your race, while your training is tapered right down. For a 70kg athlete that is 560g to 840g of carbohydrate a day, which is roughly double a normal training day. Done properly it lifts muscle glycogen (the storage form of carbohydrate sitting in your muscles) from around 100 to 120mmol/kg up to 150 to 250mmol/kg, and it is only worth doing for races longer than about 90 minutes.

Almost every triathlete I meet thinks they know how to carb load, and almost every one of them is doing a version of it that involves a giant bowl of pasta on Saturday night and a quiet hope that it will be enough.

It is not enough. One meal is not a carb load. Two days of deliberate, boring, well practised eating is a carb load, and the difference between the two shows up at about the 30km mark of your Ironman run when one of you still has fuel in the tank and the other is walking the aid stations doing sums.

This is the plan I give my athletes. Real food, real numbers, real meals you can actually eat without feeling like a stuffed sausage on the start line.

What Does Carb Loading Actually Do?

Carb loading maximises the amount of glycogen packed into your muscles and liver before the gun goes off. Your muscles hold around 100 to 120mmol/kg wet weight in a normal trained state. Load properly and you can push that to 150 to 250mmol/kg, which buys you extra time before fatigue sets in.

Note what that sentence does not say. Carb loading does not make you faster. It delays the point at which you slow down, which for a long course triathlete is the same thing in practice but a very different thing in your head. If you go out at a pace your fitness cannot hold, no amount of stored glycogen will save you.

The classic research on this is still the best. Sherman and colleagues compared three different exercise and diet regimens before a 20.9km run and found that a straightforward three days of moderate carbohydrate followed by three days of high carbohydrate lifted muscle glycogen to 203mmol/kg, versus 159mmol/kg on a moderate diet alone (Sherman, Costill, Fink & Miller, 1981, International Journal of Sports Medicine). Crucially, the brutal depletion phase that the old-school protocols insisted on made almost no difference to the final number. You do not have to wreck yourself first.

Why Is 48 Hours Enough for Carb Loading for Triathlon?

Because the research says so, and because two days is a length of time a working adult can actually execute.

Bussau and colleagues fed trained athletes 10g of high glycaemic index carbohydrate per kilogram of body weight per day and kept them physically inactive. Muscle glycogen hit maximal values within 24 hours, and eating that way for a further two days added nothing (Bussau, Fairchild, Rao, Steele & Fournier, 2002, European Journal of Applied Physiology). One day of proper loading with a genuine taper does the job.

So why do I plan for 48 hours rather than 24? Because almost nobody hits their target on day one. Life gets in the way, you travel, you get to the end of the day 200g short and you have run out of appetite. Two days gives you a buffer, and it means a shortfall on Friday does not sink your Sunday.

If your race is longer than about 90 minutes, then a 48-hour load is worth doing. If your race is under 90 minutes, then it is not, and you can put the pasta down.

Which Races Actually Need a Carb Load?

How Many Grams of Carbohydrate Do You Need?

Work off your body weight, not off how big the plate looks. Here is what the targets translate to in grams per day.

To make that tangible: 700g of carbohydrate is about 24 slices of white bread. Nobody is eating that by accident, and nobody is eating it in three meals either. You need six feeds a day and you need to start at breakfast.

What Does the 48-Hour Carb Loading Plan Look Like, Meal by Meal?

Here is a full day at roughly 700g of carbohydrate, which is 10g/kg for a 70kg athlete. Scale the portions up or down against the table above. Repeat it twice, on race minus two and race minus one.

Notice what is missing. There is very little fat, very little fibre and no beer (sorry). Fat and fibre fill you up long before the carbohydrate target is met, and fibre sitting in your gut on race morning is exactly the thing you do not want. This is the one week of the year I will happily tell you to choose white bread over wholegrain.

Notice too that liquid carbohydrate is doing a lot of the work. Juice, sports drink and flavoured milk get you to the number when chewing has become a chore.

Why Do You Feel Heavy and Bloated When You Carb Load?

Because you are, and that is the plan working.

Glycogen is stored in muscle with water bound to it. Fernandez-Elias and colleagues confirmed the long held 1:3 ratio, showing that each gram of glycogen is stored with at least 3g of water (Fernandez-Elias et al., 2015, European Journal of Applied Physiology). Fill your tank properly and you can put on 1 to 2kg of scale weight in 48 hours. That is not fat and it is not a failed taper. It is fuel plus the water that comes with it, and that water is doing you a favour on a hot day in Cairns.

If you step on the scales during race week and panic, then stay off the scales during race week. If the bloating is genuinely uncomfortable rather than just unfamiliar, then shift more of your intake to liquid carbohydrate and drop the fibre further.

What Are the Most Common Carb Loading Mistakes?

• Loading without a taper. If you are still training hard on Friday, you are burning the glycogen as fast as you store it. The taper (the deliberate drop in training volume before a race) is not optional, it is half the protocol.
• Adding food instead of swapping it. A carb load is not your normal diet plus a lasagne. Fat and protein come down, carbohydrate goes up, total energy rises only modestly.
• Garbo-loading. Hot chips, croissants and chocolate are mostly fat. You will feel disgusting and still miss your carbohydrate target.
• Loading for a sprint. Your fuel tank is already full enough for 75 minutes of racing. Save the effort.
• Doing it for the first time on race week. Never try anything new on race day, and that includes the two days before it.

How Do You Practise a Carb Load Before Race Week?

Pick a recovery week eight to ten weeks out and run the full 48 hours exactly as you would for the race. Same foods, same timing, same volume. Then do an easy session at the end of it and see how your gut feels.

You are testing three things: whether you can physically eat that much, whether your gut tolerates it, and how much weight you put on so the number does not spook you on race week. Write it down. That becomes your plan, and you stop rebuilding it from scratch every season.

Once the load is sorted, the next piece is what you take in during the race itself. I have written about why chasing the biggest number is the wrong goal in Carbs Per Hour for Triathlon: Why More Isn't Always Faster, and if you are still not convinced loading is worth the effort, have a read of Is Carb Loading a Myth? What the 2026 Research Says. Your fluid and sodium plan sits alongside all of this, and you can work yours out with the sweat rate test at home.

Frequently Asked Questions

Q: How many days before a triathlon should you carb load?
A: Two days. Start 48 hours out and treat both days the same, at 8 to 12g of carbohydrate per kilogram of body weight per day. Research shows 24 hours of proper loading with an exercise taper is enough to maximise muscle glycogen, but planning for 48 hours gives you a buffer if you fall short on the first day.

Q: How much weight will I put on when I carb load?
A: Usually 1 to 2kg over 48 hours. Glycogen is stored with at least 3g of water for every 1g of glycogen, so the gain is stored fuel and the water bound to it, not fat. Stay off the scales during race week.

Q: Do you need to carb load for a sprint or Olympic distance triathlon?
A: No for a sprint, because your existing glycogen stores comfortably cover 60 to 90 minutes of racing. For Olympic distance a light top-up of 6 to 8g/kg in the 24 hours beforehand is enough. A full 48-hour load is for races over about 90 minutes, so 70.3 and Ironman.

Q: What foods are best for carb loading?
A: Low fibre, low fat, carbohydrate dense options: white rice, white pasta, white bread, crumpets, raisin toast, potato, banana, mango, tinned fruit, honey, jam, juice, sports drink and flavoured yoghurt or milk. Keep fat and fibre low, because both fill you up before you reach your carbohydrate target and leave residue in your gut on race morning.

Q: Can you carb load and still lose weight?
A: Not in the same 48 hours, and you should not try. Race week is for fuelling, not for body composition work. Any scale change over those two days is glycogen and water, and it will settle within a few days of the race.

Q: Does carb loading make you faster?
A: Not directly. It delays the point at which fatigue sets in, which lets you hold your pace for longer and finish stronger over a set distance. It cannot compensate for pacing above your fitness or for a race day fuelling plan you have never practised.

Bottom Line

Carb loading for triathlon is two boring days of eating a lot of low fibre carbohydrate while you barely train. It is 8 to 12g per kilogram of body weight per day, six feeds a day, and about 1 to 2kg on the scales that you should ignore. It works for anything over 90 minutes and it does nothing for a sprint.

If your last race week felt like guesswork, do not stress. This is one of the easiest parts of triathlon nutrition to get right once someone shows you the numbers and you practise it once. Everything else, the daily eating that actually builds the engine, is the bigger job.

If you want the whole system rather than just race week, start with the Triathlon Nutrition Kickstart course. It walks you through your daily fuelling, your race nutrition and your carb load, so you turn up to your next start line knowing exactly what you are doing instead of hoping the pasta was enough.