I tried the old six-day depletion protocol before a gran fondo about eight years ago. By day two of the low-carb phase, I was snapping at everyone, could barely get out of bed, and my legs felt like they belonged to someone else. Three days of misery followed by three days of cramming pasta — and I still hit the wall at 140km. The protocol was supposed to supercompensate my glycogen stores. What it actually did was wreck my mental state and leave me racing on fumes.
Turns out I was following a model that Bussau and colleagues dismantled back in 2002. One day. That's all it takes. One day of eating 10-12g of carbohydrate per kilogram of body weight, combined with rest, produces full glycogen supercompensation — no depletion ride, no low-carb suffering, no six-day ordeal. The World Tour nutritionists dropped the old protocol years ago. Most amateurs are still doing it the hard way.
What Glycogen Supercompensation Actually Is
The science is clear once you see it.
Your muscles store carbohydrate as glycogen. Think of glycogen as your body's high-octane fuel tank — it's the energy source your muscles pull from during moderate-to-hard efforts. A well-fed, untrained individual stores roughly 350-500g of glycogen across their muscles and liver. A trained cyclist stores more, maybe 400-600g, because trained muscles develop better glycogen storage capacity.
Glycogen supercompensation is the process of pushing those stores beyond their normal capacity. Not just filling the tank — overfilling it. When done properly, you can increase muscle glycogen by 50-100% above normal resting levels. That translates to an extra 300-500 calories of stored carbohydrate fuel. In a race that lasts 4-6 hours, that's the difference between riding strong to the finish and completely falling apart in the final hour.
Professor Louise Burke at the Australian Institute of Sport has published extensively on this. Her work shows that supercompensation doesn't just give you more fuel — it changes the rate at which your body accesses it. Higher glycogen stores mean your muscles can maintain carbohydrate oxidation for longer before the tank runs dry. And when the tank runs dry, you bonk. Simple as that.
The Old Protocol: Why It's Dead
The original glycogen supercompensation protocol came from Scandinavian research in the late 1960s — Bergstrom and Hultman. Six days before your event, you'd do an exhaustive exercise bout to completely deplete muscle glycogen. Then for three days, you'd eat a very low-carbohydrate diet — forcing your muscles into a carb-starved state. Then for the final three days, you'd switch to extremely high carbohydrate.
The theory was that the depletion phase triggered an overcompensation response — like compressing a spring. Starve the muscles, then flood them with carbs, and they'd store more than they otherwise would.
The problem? It was absolutely miserable. Those three low-carb days left riders feeling flat, irritable, unable to train, and mentally shattered before the race even started. I tried it once before a gran fondo about eight years ago. By day two of the low-carb phase I was snapping at everyone, could barely get out of bed, and my legs felt like they belonged to someone else. Not exactly the ideal mental state heading into a target event.
And here's where it gets interesting. The depletion phase turns out to be completely unnecessary.
The Bussau Study: One Day Is Enough
In 2002, Bussau and colleagues at the University of Western Australia published a study that changed the game. They took well-trained cyclists and had them do just one day of high carbohydrate intake — roughly 10g per kg of body weight — combined with rest and no prior depletion. No exhaustive rides. No three-day carb restriction. Just one day of eating a lot of carbs and resting.
The result: muscle glycogen levels were supercompensated to the same degree as the old six-day protocol. Same endpoint. None of the suffering.
This wasn't a one-off finding. Sherman and colleagues had started poking holes in the depletion myth in the 1980s, showing that a gradual taper with three days of high carbs achieved supercompensation without depletion. Bussau pushed it further — proving even three days was more than necessary.
Burke's subsequent work reinforced this. Her recommendation, now the standard position across elite sport, is 36-48 hours of high carbohydrate intake — 10-12g per kg of body weight per day — combined with a training taper. No depletion phase. No low-carb days. Just rest and eat.
The Numbers: What 10-12g/kg Actually Looks Like
This is where most people underestimate the challenge. Let me make it concrete.
A 75kg rider needs 750-900g of carbohydrate per day during the loading phase. That is a lot of food. To put it in perspective, a large bowl of pasta contains roughly 80-100g of carbs. A large bowl of white rice is similar. A banana has about 25g. A bagel has about 50g.
You can see the problem with the "pasta party" approach immediately. Even if you eat a truly enormous bowl of pasta for dinner — 150g of carbs — you're still 600-750g short for the day. One meal cannot get you there. This is a whole-day project.
Here's what a loading day might look like for that 75kg rider:
Breakfast: Large bowl of porridge made with milk (60g carbs), two slices of white toast with jam (50g), a glass of orange juice (30g), a banana (25g). Total: ~165g.
Mid-morning snack: Two bagels with honey (110g), a sports drink (40g). Total: ~150g.
Lunch: Large portion of white rice with chicken and a sweet sauce (100g carbs), a bread roll (30g), fruit juice (30g). Total: ~160g.
Afternoon snack: Rice cakes with jam (40g), a smoothie with banana and honey (50g). Total: ~90g.
Dinner: Large portion of white pasta with a tomato-based sauce (100g carbs), garlic bread (40g), fruit juice (30g). Total: ~170g.
Evening snack: Toast with honey (40g), a glass of milk (15g). Total: ~55g.
Day total: ~790g of carbohydrate.
That's five to six meals across the day. Not three. You're essentially eating every 2-3 hours and every meal is anchored around carbohydrates. This is not intuitive eating — it requires planning.
The Fibre Problem Nobody Warns You About
Here's where it gets practical and slightly unglamorous. When you're trying to eat 800g of carbs in a day, fibre is your enemy.
High-fibre carbohydrate sources — wholegrain bread, brown rice, bran cereals, beans — fill you up fast and slow gastric emptying. You'll feel stuffed before you've eaten enough. Worse, the fibre can cause bloating and GI distress the next day — exactly what you don't want on race morning.
This is one of the few times in your life where white bread is better than brown. White rice over brown rice. Regular pasta over wholegrain. Fruit juice over whole fruit. Potatoes without the skin. Maximum carbohydrate density with minimum gut disruption.
Burke recommends keeping fat intake low during loading days too. Not because fat is harmful, but because fat is filling. If you eat a high-fat meal, you physically can't fit in enough carbs. This isn't a normal eating day. This is strategic fueling.
Liquid carbohydrates are your secret weapon here. Sports drinks, fruit juice, smoothies, even flat cola — they deliver carbs without filling your stomach the way solid food does. If you're struggling to hit your targets with food alone, drinking 200-300g of your daily carbs makes the whole thing much more manageable.
The Weight Gain Fear: It's Water, Not Fat
Every rider who carb loads properly for the first time has the same reaction when they step on the scales: panic. You'll gain 1-2kg. Maybe even 2.5kg.
This is not fat. Let me be really clear about this.
Every gram of glycogen is stored with approximately 3g of water. If you store an extra 300-400g of glycogen through supercompensation, that comes with 900-1200g of water. That's 1.2-1.6kg of total weight gain right there — glycogen plus water. It's fuel, sitting in your muscles, ready to be burned.
This is one of the most fixable psychological barriers in race preparation. Riders see the scale go up and panic. They eat less. They do a hard ride the day before to "burn it off." They undo the entire loading process because of a number on a bathroom scale.
Think of it this way: you wouldn't drive to the start of a 500km road trip with a quarter tank of fuel because you were worried about the weight of the petrol. The extra weight from carb loading is your fuel. It's what keeps you going when the rider next to you is hitting the wall.
Within 24-48 hours after the event, you'll be back to your normal weight as the glycogen and water are metabolised and excreted. This is temporary. Completely temporary.
When to Load: The 36-48 Hour Window
Timing depends on your event, but the general approach is this:
For a Sunday morning event, your loading phase runs from Friday evening through Saturday. That gives you roughly 36 hours of elevated carbohydrate intake. Some riders start Friday lunchtime for a more conservative 48-hour window.
During this period, training should be minimal. An easy 30-minute spin on Saturday morning if you need to shake out the legs. Nothing more. The rest component is critical — muscle glycogen storage requires rest. A hard training ride the day before your event when you're trying to supercompensate is self-defeating.
Jeukendrup's practical recommendation is clear: two days out from your event, increase carbohydrate intake to 10-12g/kg/day and reduce training to near zero. The day before the event, continue the high carb intake. Race morning, eat your normal pre-race breakfast (2-3g/kg, three hours out) and you'll start with glycogen stores that are 50-100% above baseline.
Why This Matters: The Performance Difference
You might be wondering whether all this effort is worth it for a single event. Here's the maths.
A typical cyclist working at moderate-to-hard intensity burns through roughly 2-3g of glycogen per minute from muscle stores. In a 4-hour sportive, that's 480-720g of glycogen. Normal resting stores of 400-600g are barely enough to cover it, even before you factor in the higher intensities of climbs and surges.
With supercompensated stores of 600-900g, you have a significantly larger buffer. You can maintain carbohydrate oxidation for longer. You delay the switch to fat oxidation — which is a slower energy pathway that can't support high-intensity efforts. The practical result is that you feel stronger in the final 60-90 minutes, the period where races and personal bests are won or lost.
A meta-analysis in the British Journal of Sports Medicine confirmed that pre-exercise carbohydrate loading improved endurance performance by an average of 2-3% in events lasting longer than 90 minutes. On a 5-hour sportive, that's 6-9 minutes. On a hilly gran fondo where the last hour is decisive, it's the difference between riding to the line and crawling to it.
The Pasta Party Myth
I've nothing against pasta. I eat it regularly. But the cultural tradition of the pre-race pasta party has done more harm than good for amateur cyclists.
The problem is threefold. First, one large meal at dinner is not carb loading. It's one meal. You need 750-900g of carbs across an entire day, spread across 5-6 meals. A pasta dinner delivers maybe 150g. You're 600g short.
Second, eating a massive meal the night before a race often causes GI discomfort the next morning. Bloating, poor sleep, a sluggish feeling at the start line.
Third, the pasta party creates a false sense of security. Riders think they've carb loaded because they had a big pasta dinner, so they skip the high-carb breakfast and don't eat enough during the day before. They arrive at the start line with normal glycogen stores, not supercompensated ones, and wonder why they fade.
The fix is a mindset shift. Carb loading is a 24-48 hour process, not a single meal. It's about total carbohydrate intake across the entire loading window, distributed evenly throughout the day. The pasta dinner can be part of it — but it's one piece, not the whole thing.
A Practical Protocol You Can Follow
Here's the step-by-step for a Sunday event:
Thursday: Normal training, normal diet. This is your last proper session before the event — an easy opener ride or a short sharpener if your coach prescribes one.
Friday afternoon/evening: Begin loading phase. Increase carb intake to 10-12g/kg. Shift toward low-fibre, easily digestible carbohydrate sources. Include liquid carbs to help hit targets. No training or only very light movement.
Saturday (all day): Continue loading. 10-12g/kg across 5-6 meals. Rest or a very easy 20-30 minute spin. Hydrate with electrolyte drinks (which also add carbs). Lay out all race day nutrition and equipment.
Saturday evening: Familiar carb-rich dinner. Not a massive blowout — a normal-sized but carb-dense meal. Go to bed at your normal time.
Sunday morning: Race day breakfast 3 hours before the start. 2-3g/kg of carbs. Then execute your in-race fueling plan.
One important note: if this is your first time carb loading properly, practise it before a training weekend first. You need to know what foods work for your stomach, what quantities feel manageable, and how your body responds to the temporary weight gain. Don't trial a new nutrition strategy on the day it matters most.
Who Should Actually Carb Load
Let me be direct: carb loading is most beneficial for events lasting longer than 90 minutes at moderate-to-high intensity. If your event is a 40-minute crit or a short time trial, glycogen depletion isn't your limiter. Your normal diet with a good pre-race meal will cover it.
Where carb loading really pays off:
- Sportives and gran fondos over 3 hours
- Road races over 2.5 hours
- Multi-day events (load before each stage)
- Hilly events where intensity is variable and glycogen demand spikes on climbs
- Any event where you've previously "hit the wall" in the final third
The longer and harder your event, the more supercompensation matters. For an Etape du Tour, a Marmotte, a Dragon Ride — these are exactly the events where the extra 300-500 calories of stored glycogen keeps you riding when others are surviving.
The Bigger Picture
Carb loading is one piece of a larger race nutrition strategy. It sets the starting point — how much fuel you begin with. But it doesn't replace in-race fueling. Even with fully supercompensated glycogen stores, you'll deplete them over 3-4 hours of hard riding if you don't eat on the bike. Supercompensation and in-race fueling work together, not as alternatives.
Think of it like this: carb loading fills the main tank. In-race nutrition is the auxiliary tank. You need both.
Unlike fitness, which takes months to build, a properly loaded fuel tank is something you can achieve in 24-48 hours. That's the kind of free speed that's hard to argue with.
If you want to go deeper on race nutrition — the hour-by-hour fueling plan, gut training, caffeine timing, and the mistakes that kill performance before you even get to the start line — come join us in the Roadman Cycling community on Skool. We'll help you build a plan that actually works for your events.