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What to Eat Before and After Running

Published 26 July 2026 · 10 min read

Most running nutrition advice is written for marathon runners and then applied, badly, to people going out for 4 kilometres. The right answer depends almost entirely on how long you are running.

The rule that determines everything: 60 minutes

Your body stores roughly 400 to 500 grams of glycogen — carbohydrate — across the liver and skeletal muscle. That represents around 1,600 to 2,000 kcal of readily available fuel, which is enough for approximately 90 minutes of moderate running before stores become limiting.

This single fact resolves most nutrition questions. If your run is under an hour, you already have all the fuel you need. Eating beforehand is optional and mostly about comfort. Once runs extend past 75 to 90 minutes, fuelling stops being optional and starts being the difference between finishing well and grinding to a halt.

Timing: how long before you run

Digestion competes with running for blood flow. Eat too close to a run and blood that your gut needs for digestion is being diverted to your legs, which produces cramping, nausea, and the specific misery of a sloshing stomach.

Time before run	What works
3–4 hours	Full balanced meal — carbs, protein, some fat
2 hours	Moderate carb-focused meal, low fat and fibre
1 hour	Small simple-carb snack: banana, toast with honey
30 minutes or less	Liquid carbohydrate only, or nothing

Fat and fibre both slow gastric emptying considerably. A high-fat meal can sit in the stomach for four hours or more. This is why the classic pre-race breakfast is white toast with jam rather than eggs and avocado — refined carbohydrate clears quickly and is precisely what you want it to.

What actually to eat before a run

Two to three hours out: porridge with banana and honey; white rice with a small portion of lean protein; a bagel with jam; pasta with a light tomato sauce. Aim for roughly 1 to 2 grams of carbohydrate per kilogram of body weight.

Thirty to sixty minutes out: a banana, a slice of white bread with honey, a handful of dried dates, a sports drink. Small, simple, low fibre.

What to avoid before running: anything high in fat, anything high in fibre, large volumes of dairy if you are at all sensitive to it, and anything you have not eaten before a run previously. Race morning is not the time to try a new breakfast.

Fasted running: does it work?

Running before breakfast shifts substrate use towards fat oxidation — with low glycogen availability, the body draws proportionally more energy from fat. This is genuine physiology and it is why fasted running has a following.

What it does not do is increase total fat loss. Over a 24-hour period, the body balances substrate use, and a fasted run followed by a normal day produces essentially the same net energy balance as a fed run. Controlled trials comparing fasted and fed training for body composition consistently find no meaningful difference when total calories are matched.

Where fasted running is genuinely useful is convenience and gut training. If you prefer running first thing without organising food around it, do that. If your stomach is unhappy with anything eaten before a run, fasted running solves the problem. Both are good reasons. Accelerated fat loss is not.

The caveat: fasted running works poorly for hard sessions. Intervals, tempo runs, and anything above easy pace depend heavily on glycogen. Save fasted running for easy efforts.

Fuelling during long runs

Past 75 to 90 minutes, glycogen depletion becomes the limiting factor. This is the physiological basis of "hitting the wall" — the abrupt drop in pace and mood familiar to anyone who has run a marathon without fuelling adequately.

The standard recommendation is 30 to 60 grams of carbohydrate per hour for runs beyond 90 minutes, starting at around the 45-minute mark rather than waiting until you feel depleted. Once you are empty, you cannot absorb carbohydrate fast enough to recover mid-run.

Options, all roughly interchangeable:

• Energy gels — 20–25 g carbohydrate each, easy to carry, require water alongside
• Sports drinks — carbohydrate plus fluid plus sodium in one, but bulky to carry
• Dried dates or raisins — real food, cheap, work perfectly well
• Bananas — around 25 g carbohydrate, awkward to carry but effective

Whatever you choose, practise it in training. Gut tolerance for carbohydrate during exercise is trainable, and the runners who take gels for the first time on race day are the ones who discover they cannot tolerate them at kilometre 30.

Hydration without overthinking it

For runs under an hour in moderate conditions, drinking to thirst is sufficient. The concern about dehydration in short runs is overstated for most people in most climates.

For longer runs, particularly in heat, aim for roughly 400 to 800 ml per hour, adjusted for how much you sweat. You can estimate your sweat rate by weighing yourself before and after a run: each kilogram lost is approximately one litre of fluid.

Sodium matters for runs beyond about two hours or in significant heat. Sweat contains 400 to 1,500 mg of sodium per litre depending on the individual. Replacing it with an electrolyte drink or salt tablets prevents the fatigue and cramping associated with sodium depletion, and — more importantly — reduces the risk of hyponatraemia, which is caused by drinking large volumes of plain water without replacing salt.

The genuine risk to be aware of: drinking substantially more than you sweat over a long event is dangerous. Hyponatraemia is rare but serious, and it is caused by over-hydration, not under-hydration.

After the run

Recovery nutrition has been oversold. The "anabolic window" — the idea that you must eat within 30 minutes or lose the training benefit — has not held up well in more recent research. For most runners eating normal meals across the day, the window is more like several hours, and total daily intake matters far more than precise timing.

Timing does become relevant in two situations: when you are training twice in one day, and when you are running again within about eight hours. In both cases, getting carbohydrate in quickly measurably speeds glycogen resynthesis.

For everyone else: a meal containing carbohydrate and 20 to 30 grams of protein within a couple of hours of finishing is entirely sufficient. Eggs on toast, yoghurt with fruit and granola, a chicken and rice bowl, or a protein shake with a banana all do the job. There is no need for anything specialised.

Running and weight loss: the honest version

A 70 kg runner burns approximately 350 kcal over a 5K. That is real, but it is also roughly one pastry, and it is far easier to eat 350 kcal than to run them off.

There is also a well-documented compensation effect: people who start running frequently increase food intake, often unconsciously, and become less active outside their runs. Studies measuring total daily energy expenditure consistently find that adding exercise increases it by less than the exercise itself would predict.

None of this means running is useless for body composition. It means running works best as one component alongside attention to food intake, and it means expecting weight loss proportional to calories burned will lead to disappointment. Use the calorie calculator to understand the scale of what you are burning, then treat that figure as information rather than as a licence.

Practical summary

• Runs under an hour need no special fuelling
• Eat 2–3 hours before if you want a full meal; 30–60 minutes before if you want a small snack
• Keep pre-run food low in fat and fibre
• Fuel with 30–60 g of carbohydrate per hour beyond 90 minutes
• Drink to thirst on short runs; add sodium beyond two hours
• Post-run: carbohydrate plus protein within a couple of hours, no urgency beyond that
• Never try new food on race day

This article is general information, not personalised dietary advice. If you have diabetes, a history of disordered eating, or any medical condition affected by diet or exercise, consult a registered dietitian or your doctor.