Quick answer
- Eat a carbohydrate-focused, low-fat, low-fibre meal of roughly 1 to 2 grams of carbohydrate per kilogram of body weight two to three hours before a long run: for a 70 kg runner that is about 70 to 140 g, such as a bagel with honey plus a banana and a sports drink.
- If you are starting early, shrink it to 30 to 60 g of simple carbohydrate 45 to 90 minutes before, and lean on a good dinner the night before.
- Then fuel during the run itself, starting at 30 to 60 g of carbohydrate per hour from about the 45 to 60 minute mark, because no pre-run meal can cover a two-hour effort on its own.
5 key facts
- A long run over about 90 minutes will outlast liver glycogen, which is why the meal before and the fuel during are two separate jobs.
- The night before matters more than most runners assume, because overnight liver glycogen depletion is what makes early morning runs feel flat.
- Fat, fibre, and large protein portions slow gastric emptying and are the main causes of pre-long-run stomach trouble.
- Every long run should rehearse the fuel you intend to use on race day, including the product, the timing, and the water that goes with it.
- Running long fasted is a legitimate training tool for easy efforts, but it is a poor default for quality long runs and for any run over about two hours.
The long run is the session that exposes nutrition. A hard 40-minute run can be survived on yesterday’s dinner and stubbornness. Two hours cannot. And most of the long-run failures runners describe as "I just had a bad day" are actually a chain of three decisions: what they ate the night before, what they ate that morning, and whether they carried anything.
This guide takes those three in order, and gives you numbers rather than vibes. It is also, deliberately, a rehearsal plan: everything here is what you should be practising if there is a race at the end of the block.
Step one: the night before
Muscle glycogen survives the night largely intact. Liver glycogen does not; an overnight fast drains a meaningful portion of it, and the liver is what maintains your blood glucose. This is the physiological reason that an early long run on an empty stomach after a light dinner feels so much harder than the same run in the afternoon.
For scale, the liver holds only about 80 to 100 g of glycogen. Wake at 5:30 for a 6:00 long run and there is barely time to eat, let alone digest, so you are running mostly on what dinner stored.
You do not need a carb-loading dinner before a normal long run. You do need a normal-sized, carbohydrate-forward meal at a normal hour.
60 to 90 min
Dinner the night beforeOrdinary balanced dinner
ExampleAnything you usually eat
90 min to 2 h
Dinner the night beforeCarbohydrate-forward, moderate fibre
ExamplePasta or rice with a lean protein, bread on the side
2 to 3 h
Dinner the night beforeDeliberately carbohydrate-heavy, lower fibre
ExampleLarge pasta or rice portion, white bread, a dessert, water
Over 3 h, or a marathon-pace long run
Dinner the night beforeTreat it like a small race: high carbohydrate, low fibre, low alcohol
ExampleWhite rice, chicken, minimal vegetables, a sweet drink
| Long run length | Dinner the night before | Example |
|---|---|---|
| 60 to 90 min | Ordinary balanced dinner | Anything you usually eat |
| 90 min to 2 h | Carbohydrate-forward, moderate fibre | Pasta or rice with a lean protein, bread on the side |
| 2 to 3 h | Deliberately carbohydrate-heavy, lower fibre | Large pasta or rice portion, white bread, a dessert, water |
| Over 3 h, or a marathon-pace long run | Treat it like a small race: high carbohydrate, low fibre, low alcohol | White rice, chicken, minimal vegetables, a sweet drink |
- Keep the fibre moderate to low if you are prone to gut trouble; save the large salad for a rest day.
- Alcohol the night before a long run impairs both hydration and sleep. One drink is survivable; four is a wasted session.
- Do not go to bed hungry after a hard Friday. Under-eating on Friday is the single most common cause of a bad Saturday.
- Skip a brand-new or restaurant meal before a key long run. Tonight is not the night to test your gut.
- Do not cut dinner short because you plan to take gels tomorrow. Gels cover the run itself; they cannot refill what dinner left out.
- If tomorrow will be hot or humid, add a salty food or an electrolyte drink at dinner, drink steadily through the evening, and do not go to bed dehydrated.
Dinners that work well for many runners the night before a long run:
- Rice bowl with chicken or tofu, cooked vegetables, soy sauce, and fruit.
- Pasta with tomato sauce, lean protein, bread, and water.
- Potatoes with eggs, salt, yogurt, and a banana.
- Noodles with a familiar protein, cooked vegetables, and an electrolyte drink if the morning will be hot.
Step two: the morning of, by time available
The target for a proper pre-run meal is roughly 1 to 2 g of carbohydrate per kilogram of body weight, eaten two to three hours before you start, and kept low in fat and fibre. Below is what that looks like for different body weights and different amounts of available time.
| Time before start | Carbohydrate target | 60 kg runner | 75 kg runner | 90 kg runner |
|---|---|---|---|---|
| 3 hours | 1.5 to 2 g/kg | 90 to 120 g | 110 to 150 g | 135 to 180 g |
| 2 hours | 1 to 1.5 g/kg | 60 to 90 g | 75 to 110 g | 90 to 135 g |
| 60 to 90 min | 0.5 to 1 g/kg | 30 to 60 g | 38 to 75 g | 45 to 90 g |
| 30 min | ~0.3 g/kg, simple sugar only | ~20 g | ~25 g | ~30 g |
| Option | Carbohydrate | Fits which slot |
|---|---|---|
| Bagel with honey plus a banana | ~75 g | 2 to 3 hours |
| Porridge made with water, banana, honey, plus juice | ~100 g | 2.5 to 3 hours |
| Two slices white toast with jam | ~50 g | 90 min to 2 hours |
| Bowl of low-fibre cereal with milk | ~55 g | 90 min to 2 hours |
| Banana plus 400 ml sports drink | ~50 g | 60 to 90 min |
| One gel plus water | ~25 g | 20 to 30 min |
| Four dates | ~28 g | 30 to 45 min |
The consistent principle: the closer to the start, the simpler and smaller the food. Fat and fibre are the things to strip out, because they are what slows the stomach. That means jam rather than nut butter, white bread rather than seeded, and a fried breakfast never.
Step three: the early start problem
Almost nobody gets three hours before a Saturday long run. The realistic options are these, and the wrong one is whichever you have not practised.
Small and early
How it worksWake 60 to 90 min before, eat 30 to 60 g simple carbohydrate
Best forMost runners, most long runs
Liquid
How it worksA sports drink, diluted juice, or a low-fibre smoothie instead of solid food
Best forRunners whose stomachs refuse food at 5:30 a.m.
Eat on the move
How it worksStart with a gel or drink in the first 15 minutes and keep fuelling from there
Best forVery early starts where sleep matters more than a meal
Fasted, easy only
How it worksWater and coffee, run at genuinely easy pace, keep it under about 90 minutes
Best forEasy aerobic long runs where the goal is not quality
| Approach | How it works | Best for |
|---|---|---|
| Small and early | Wake 60 to 90 min before, eat 30 to 60 g simple carbohydrate | Most runners, most long runs |
| Liquid | A sports drink, diluted juice, or a low-fibre smoothie instead of solid food | Runners whose stomachs refuse food at 5:30 a.m. |
| Eat on the move | Start with a gel or drink in the first 15 minutes and keep fuelling from there | Very early starts where sleep matters more than a meal |
| Fasted, easy only | Water and coffee, run at genuinely easy pace, keep it under about 90 minutes | Easy aerobic long runs where the goal is not quality |
Fasted long runs deserve a clear-eyed treatment. Training with low carbohydrate availability does produce some useful metabolic adaptations, and plenty of runners do their easy long runs this way without harm. But it becomes a bad idea quickly: for any long run with quality in it, any run over about two hours, any run in the heat, and for anyone with a history of under-fuelling or disordered eating. The performance cost is real, and the recovery cost is realer.
Step four: what to take with you
No breakfast can fuel a two-hour run. The pre-run meal tops up liver glycogen and settles blood sugar; the fuel you carry is what keeps carbohydrate arriving once the run is longer than your stores comfortably cover.
Under 60 min
Carbohydrate duringNone needed
Practical formWater
60 to 90 min
Carbohydrate during0 to 30 g total
Practical formOptional gel or sports drink, mainly to practise
90 min to 2 h
Carbohydrate during30 to 60 g per hour
Practical formOne to two gels per hour, or 500 ml sports drink plus a gel
2 to 3 h
Carbohydrate during60 g per hour
Practical formTwo gels per hour with water, or a drink mix plus chews
Over 3 h
Carbohydrate during60 to 90 g per hour if trained for it
Practical formGlucose-fructose blends; mix formats to avoid flavour fatigue
| Run length | Carbohydrate during | Practical form |
|---|---|---|
| Under 60 min | None needed | Water |
| 60 to 90 min | 0 to 30 g total | Optional gel or sports drink, mainly to practise |
| 90 min to 2 h | 30 to 60 g per hour | One to two gels per hour, or 500 ml sports drink plus a gel |
| 2 to 3 h | 60 g per hour | Two gels per hour with water, or a drink mix plus chews |
| Over 3 h | 60 to 90 g per hour if trained for it | Glucose-fructose blends; mix formats to avoid flavour fatigue |
- Start fuelling at around 45 to 60 minutes, not when you feel empty. Once you feel empty it is too late to catch up.
- Set a repeating timer rather than relying on how you feel. Judgement is the first thing fatigue takes.
- Always take a gel with water. A gel swallowed dry is a concentrated syrup that pulls water into your gut and is a leading cause of mid-run cramping.
- Use the exact products you intend to race with. The long run is the only realistic place to find out that a flavour turns your stomach at hour two.
- Build up gradually. Going from nothing to 90 g per hour in one weekend will not work; the gut adapts over weeks.
A worked Saturday
Friday 19:00
ActionDinner
DetailRice or pasta with lean protein, low fibre, no alcohol
Friday 21:30
ActionOptional snack
DetailYoghurt and honey, or cereal, if dinner was early
06:15
ActionWake, 400 ml water
DetailRehydrate before anything else
06:25
ActionBreakfast
DetailBagel with honey and a banana, about 75 g carbohydrate
07:45
ActionCoffee if you use it, final toilet stop
DetailSips of fluid only from here
08:00
ActionStart 2 h 15 long run
DetailTimer set for the first gel at 08:50
08:50, 09:20, 09:50
ActionFuel
DetailOne gel with water at each, roughly 60 g per hour
10:15
ActionFinish, then recovery within the hour
Detail60 to 90 g carbohydrate plus 25 g protein
Rest of day
ActionKeep eating
DetailA long run is not paid off by one recovery shake
| Time | Action | Detail |
|---|---|---|
| Friday 19:00 | Dinner | Rice or pasta with lean protein, low fibre, no alcohol |
| Friday 21:30 | Optional snack | Yoghurt and honey, or cereal, if dinner was early |
| 06:15 | Wake, 400 ml water | Rehydrate before anything else |
| 06:25 | Breakfast | Bagel with honey and a banana, about 75 g carbohydrate |
| 07:45 | Coffee if you use it, final toilet stop | Sips of fluid only from here |
| 08:00 | Start 2 h 15 long run | Timer set for the first gel at 08:50 |
| 08:50, 09:20, 09:50 | Fuel | One gel with water at each, roughly 60 g per hour |
| 10:15 | Finish, then recovery within the hour | 60 to 90 g carbohydrate plus 25 g protein |
| Rest of day | Keep eating | A long run is not paid off by one recovery shake |
The mistakes that cause bad long runs
- Under-eating on Friday, then blaming Saturday morning’s breakfast.
- Eating something high in fat or fibre 90 minutes before starting.
- Carrying nothing on a two-hour run because "it is only training".
- Waiting until you feel low to take the first gel.
- Taking gels without water and then concluding that gels do not agree with you.
- Trying a brand-new product on the longest run of the block.
- Drinking a large volume in the final 20 minutes before starting, which is a reliable way to produce a side stitch.
Frequently asked questions
What should I eat before a long run?
A carbohydrate-focused, low-fat, low-fibre meal of roughly 1 to 2 g of carbohydrate per kilogram of body weight, two to three hours before. A bagel with honey and a banana, porridge made with water plus juice, or toast with jam all work well.
What should I eat before a 20 mile run?
Treat it as a race rehearsal: a carbohydrate-heavy, low-fibre dinner the night before, then 1.5 to 2 g of carbohydrate per kg two to three hours before the start, and 60 g of carbohydrate per hour during the run using the exact products you plan to race with.
Should I eat before an early morning long run?
Yes for anything over about 90 minutes or with quality in it. If time is short, eat 30 to 60 g of simple carbohydrate 45 to 90 minutes before, or take it in liquid form. Running easy and short can be done fasted if you have practised it.
How long before a long run should I eat?
Two to three hours for a full meal. If you have 60 to 90 minutes, halve the portion. In the last 30 minutes, only simple sugar such as a gel, dates, or a sports drink.
What should I eat the night before a long run?
A normal-sized, carbohydrate-forward dinner at your usual time, lower in fibre than usual if your stomach is sensitive, and light on alcohol. You do not need to carb load for a training long run, but you should not go to bed short.
What foods should I avoid the night before a long run?
Avoid unfamiliar or restaurant meals, very high-fat dinners, a lot of fibre if your stomach is sensitive, and alcohol. Also avoid eating a smaller dinner because you plan to take gels during the run.
How much should I drink before a long run?
About 400 to 500 ml on waking, then normal fluid with breakfast, then only sips in the final 20 to 30 minutes. Large volumes immediately before starting cause sloshing and side stitches without improving hydration.
Sources
- 1Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and ACSM: Nutrition and Athletic PerformanceMedicine and Science in Sports and Exercise (Thomas et al., 2016)Pre-exercise meal targets of 1 to 4 g carbohydrate per kg and during-exercise intakes
- 2Nutrition for Endurance Sports: Marathon, Triathlon, and Road CyclingJournal of Sports Sciences (Jeukendrup, 2011)Carbohydrate intake rates during long endurance sessions
- 3Training the Gut for AthletesSports Medicine (Jeukendrup, 2017)Why in-run fuelling tolerance must be built gradually
- 4Carbohydrates for Training and CompetitionJournal of Sports Sciences (Burke et al., 2011)Pre-session fuelling and the role of liver glycogen overnight
General guidance for healthy adults, not medical advice. Talk to a doctor or registered dietitian if you have a health condition, take medicines or have special dietary needs.
