Running Nutrition Mistakes: What Most Runners Get Wrong
Most runners will happily spend six months building a training block, argue about shoe stack heights for an hour, and then turn up to a marathon having given about four minutes of thought to what they are going to eat. It shows. Walk the last 10k of any big-city marathon in the four-hour zone and you will see the consequences: shuffling, cramping, glassy-eyed people who trained perfectly well and simply ran out of fuel.
The frustrating part is that fuelling is one of the few areas of endurance sport where the fixes are cheap, fast and almost embarrassingly effective. You cannot add 5% to your VO2 max in a fortnight. You absolutely can add 30 grammes of carbohydrate per hour to your race plan and hold pace for an extra 8 kilometres. Below are the running nutrition mistakes I see most often, why they happen, and what to do instead.
Mistake one: under-fuelling anything over 90 minutes
A trained runner stores roughly 400 to 500 grammes of glycogen across muscle and liver — call it 1,600 to 2,000 kcal of readily available carbohydrate. At marathon effort you are burning somewhere between 60 and 80% of your energy from carbohydrate, which means the tank empties in around 90 to 120 minutes of hard running. That is the wall, and it is arithmetic rather than willpower.
The current guidance from the sports nutrition literature is clear enough: for efforts of 1 to 2.5 hours, aim for 30 to 60g of carbohydrate per hour. Beyond 2.5 hours, push towards 60 to 90g per hour. Elite marathoners are now routinely taking 90 to 100g/hr, which would have been considered reckless a decade ago.
Where most runners go wrong is starting too late. If you take your first fuel at 45 minutes because you "don't feel like you need it yet", you are already digging a hole — absorption lags ingestion by 15 to 20 minutes. Start feeding at 20 to 30 minutes and keep the drip steady. Little and often beats one heroic gel at halfway every single time.
Mistake two: ignoring the type of carbohydrate, not just the amount
This is the mistake that separates runners who can tolerate 80g/hr from runners who get bloated and miserable at 45g/hr. Glucose is absorbed across the gut wall by the SGLT1 transporter, and that transporter saturates at roughly 60g per hour. Pour in more glucose and it simply sits in your gut drawing water in, which is precisely how you end up sprinting for a portaloo at 30k.
Fructose uses a completely separate transporter, GLUT5, which adds another 30 to 35g per hour of absorptive capacity. That is why multi-transportable carbohydrate blends — typically a 2:1 or 1:1 glucose-to-fructose ratio — allow total intakes of 90g/hr and above with far less gastrointestinal grief. If your fuel is pure glucose or maltodextrin, you have a hard ceiling around 60g/hr no matter how tough your stomach is.
Mistake three: never practising it in training
Your gut is trainable tissue. Repeated exposure to carbohydrate during exercise upregulates SGLT1 expression and improves gastric emptying — studies on gut training typically show meaningful improvements in tolerance within two to four weeks of consistent practice. Runners who fuel exclusively on race day are asking an untrained system to do its hardest job on its debut.
Practically: fuel every long run over 75 minutes, even the easy ones. Use the exact product, the exact flavour and the exact timing you plan to use on race day. If you are targeting 75g/hr in a marathon, you should have rehearsed 75g/hr at least three or four times in training before you pin a number on. "Nothing new on race day" is repeated so often it has become wallpaper, but it remains the single highest-value rule in the sport.
Mistake four: treating sodium and recovery as afterthoughts
Sweat sodium concentration varies enormously between individuals — anywhere from roughly 200mg to over 1,800mg per litre. If you are a salty sweater running a hot half marathon, plain water will not cut it, and no amount of carbohydrate compensates for that. Aim for 300 to 700mg of sodium per hour in warm conditions and adjust based on whether you finish with salt crusted on your face.
On the other side of the finish line, the recovery window is real even if it has been oversold. Getting 1.0 to 1.2g of carbohydrate per kilogramme of body weight plus around 20 to 25g of protein in within the first hour meaningfully accelerates glycogen resynthesis — which matters enormously if you are training again within 24 hours. For a 70kg runner that is roughly 75g of carbohydrate, not a token banana.
There is also good evidence for tart cherry as a recovery tool. Montmorency cherries are unusually rich in anthocyanins, the polyphenols responsible for their deep colour, and these have been shown to reduce markers of oxidative stress and inflammation after strenuous exercise. Trials in marathon runners have reported faster recovery of isometric strength and lower inflammatory markers when tart cherry was taken for around five to seven days around the event. It is not magic, but it is one of the better-supported recovery interventions available.
What we use at FTP Endurance Fuel
We built our pastilles around the two things above that actually move the needle: a multi-transportable carbohydrate blend so you can get past the 60g/hr glucose ceiling, and real tart cherry for the recovery side. They are chewable rather than gel-textured, which sounds trivial until you have tried to open a foil sachet with cold, wet hands at 32k.
Most of our runners settle into a rhythm of two or three pastilles every 20 minutes, which lands them comfortably in the 60 to 80g/hr band without ever feeling like they are force-feeding. The Tart Cherry Pastilles are the obvious pick if recovery and back-to-back training days are your bottleneck, while the Mixed Fruit Pastilles suit runners who get flavour fatigue on anything over three hours — and flavour fatigue is a genuine reason people stop eating mid-race. Buying the 1kg bulk pack rather than individually wrapped sachets also cuts the cost per gramme of carbohydrate substantially, which makes practising your fuelling in training far less painful financially.
None of these running nutrition mistakes require a sports science degree to fix. Start fuelling earlier than feels necessary, use a mixed-carbohydrate source so you can absorb more of it, rehearse the plan on your long runs, and take recovery seriously enough to eat properly within the hour. Do that consistently and the last 10k of your next race will feel like a different sport. If you want to test what works for you before committing to a bulk pack, the taster pack is the sensible place to start — try it on a long run this weekend and see how the final hour feels.
