By FTP Endurance Fuel.
Most people who come into endurance sport get the training part sorted long before they get the eating part sorted. You can follow a marathon plan to the letter, but if you turn up to a three-hour session with a banana and a vague sense of optimism, the last hour is going to hurt far more than it needs to. The frustrating thing is that fuelling is actually the easiest variable to control. It just gets ignored because nobody explains the basics in plain terms.
This guide covers endurance nutrition from first principles: what your body burns, how much you need per hour, what to eat before, during and after, and how to build a fuelling strategy you can actually stick to.
Quick answer: for sessions over an hour, aim for 30–60g of carbohydrate per hour, building towards 60–90g per hour on long efforts over 90 minutes using mixed glucose and fructose sources. Start fuelling in the first 20–30 minutes and eat by the clock, not by feel. Practise the plan in training and never debut it on race day.
What your body actually burns during endurance exercise
Your body runs on two main fuel tanks: fat and carbohydrate. Fat stores are effectively unlimited, as even a lean athlete carries tens of thousands of calories of it, but fat is slow-burning fuel. It can only be converted to energy at a modest rate, which is fine for easy-paced efforts but nowhere near enough once you push above roughly 70% of your maximum effort.
Carbohydrate is the fast fuel. It is stored as glycogen in your muscles and liver, and the catch is that the tank is small: most people hold around 400–500g of glycogen, roughly 1,600–2,000 calories. At a steady endurance pace you can burn through most of that in 90 minutes to two hours. When it runs out, you hit the wall. Your pace collapses, your mood collapses with it, and no amount of willpower brings the power back.
The entire point of a fuelling strategy is to keep that carbohydrate tank from emptying. Everything else is detail.
The numbers: how much carbohydrate per hour
Here are the working figures used across endurance sport, and they are worth memorising:
- Under 60 minutes: you do not need to fuel during the session. Your existing glycogen covers it, and a normal meal a couple of hours beforehand is enough.
- One to two hours: aim for 30–60g of carbohydrate per hour.
- Two to three hours: aim for 60g per hour as your baseline.
- Three hours or more: trained guts can absorb up to 90g per hour using mixed carbohydrate sources (glucose and fructose together), because the two sugars use different absorption pathways in the intestine.
For context, a typical energy chew carries 4–5g of carbohydrate, a banana around 25g and a typical gel 20–25g. So 60g per hour might look like a gel plus half a banana plus a few chews. The format matters far less than the total, so pick whatever your stomach tolerates and your pocket carries.
One crucial habit: start fuelling in the first 20–30 minutes, not when you feel tired. By the time you feel empty, you are already 30–45 minutes behind, because carbohydrate takes time to digest and reach your bloodstream. Fuel by the clock, not by feel.
| Session length | Carb target | What that looks like | |---|---|---| | Under 60 minutes | None needed | A normal meal 2–3 hours beforehand covers it | | 1–2 hours | 30–60g per hour | 2–4 FTP pastilles per hour (2 pastilles ≈ 30g), or a gel plus a banana | | 2–3 hours | 60g per hour | Roughly 2 FTP pastilles every 30 minutes, fuelled by the clock | | 3+ hours | Up to 90g per hour | Mixed glucose and fructose sources, taken every 15–20 minutes |
Before and after: the bookends that make it work
Pre-session eating does not need to be complicated. For a morning long run, a carbohydrate-based breakfast two to three hours beforehand, such as porridge, toast and jam or a bagel, tops up the liver glycogen that depletes overnight. If you train straight after waking, even 20–30g of quick carbohydrate 15 minutes before you start makes a measurable difference.
Afterwards, the priority is restocking. The standard guidance is 1–1.2g of carbohydrate per kilogram of body weight in the first hour after the session, plus 20–25g of protein for muscle repair. For a 70kg runner that is roughly 70–85g of carbohydrate, which is a proper meal rather than a snack. This matters most when you train again within 24 hours; if you have two rest days, timing is far less critical than total intake.
Hydration runs through all of this. As a starting point, drink 500–750ml per hour in moderate conditions, more in the heat, and include electrolytes (mainly sodium, 300–600mg per hour) on sessions over 90 minutes or in warm weather.
Building a strategy you will actually follow
The best fuelling plan is the one you can repeat every week without thinking. Here is a simple framework:
- Write down your longest weekly session and calculate the carbohydrate target: duration in hours multiplied by 60g.
- Choose one or two fuel formats you genuinely like eating. If you dread it, you will skip it. Pastilles and chews work well for beginners because you can dose them gradually rather than committing to a whole gel at once.
- Set a schedule. Something every 20 minutes is easier to remember than hourly totals, and at 60g per hour that is 20g every 20 minutes.
- Practise in training and never debut on race day. Your gut is trainable, and regular fuelling during sessions genuinely increases how much carbohydrate you can absorb without discomfort, but it adapts over weeks, not days.
- Keep notes. Write two lines after each long session: what you ate and how you felt. Within a month you will have a personalised plan.
Expect some trial and error. Gut discomfort in the first few fuelled sessions is common and usually settles as your digestive system adapts. If a particular product consistently upsets your stomach, switch formats before abandoning the fuelling plan itself.
What we use at FTP Endurance Fuel
We built our range around exactly the problems described above. Our Mixed Fruit Energy Pastilles (opens in a new tab) are designed for dosing flexibility, so you can eat them one at a time, which makes hitting a 60g-per-hour target far easier on a beginner's stomach than downing full gels. If you are not sure where to start, our taster pack is a low-commitment way to test whether pastilles suit your gut before buying in bulk.
Fuelling well is not complicated, but it is a skill, and like every skill in endurance sport it rewards consistent practice. Start with 60g of carbohydrate per hour on your next long run, fuel by the clock and take notes. Your last hour will thank you.
Find FTP Endurance Fuel on RLS
FTP Endurance Fuel is an RLS Partner, an independent UK endurance nutrition brand shipping from Aberdeen. Chewable energy pastilles, carbohydrate and electrolyte drink mixes and electrolyte tablets, made for long runs and long days out. Recognised in the Runner's World Sports Nutrition Awards 2026 and rated 4.8 from over 440 verified reviews. Run Love Sprint members can find FTP Endurance Fuel in RLS Rewards, along with an exclusive member offer.
