Running nutrition comes down to four decisions: how much carbohydrate you eat day to day, what you eat before a run, whether you need fuel during a run, and how you recover afterward. Get the basics of each right and most of the confusion around "what should I eat as a runner" disappears. None of it needs to be complicated, and very little of it needs to be expensive.
How much should runners eat day to day?
Running nutrition doesn't start on race morning. It starts with what fills your plate on an ordinary Tuesday. Carbohydrate is the nutrient runners tend to under-eat, often because of general "carbs are bad" messaging that has nothing to do with training load.
The American College of Sports Medicine recommends daily carbohydrate intake of roughly 3 to 12 g per kg of bodyweight, scaled to how much you're training (Thomas et al., 2016). Someone running three easy sessions a week sits toward the lower end of that range. Someone building volume for a half marathon or marathon, especially with back-to-back long runs, needs to sit higher. Protein matters too, for muscle repair and general recovery, but carbohydrate is the one runners most often shortchange without realising it.
A simple gut check: if your legs feel flat on runs that should feel manageable, or your easy pace suddenly feels hard, chronic under-fuelling is worth ruling out before assuming it's a fitness problem.
What should you eat before a run?
Timing matters more than the specific food. Two windows work well for most runners:
- 3 to 4 hours before: a proper meal, mostly carbohydrate, with moderate protein and lower fat and fibre so it has time to digest. Think rice with chicken, or toast with eggs and banana.
- 30 to 60 minutes before: something small and easily digested if you need a top-up. A banana, a slice of toast with honey, or a small handful of dried fruit all work.
Fat, fibre and very large portions close to a run are the usual culprits behind heavy legs and stomach discomfort at the start line. The closer you get to run time, the smaller and simpler the meal should be.
Do you need to eat or drink during a run?
For most runs, no. If you're out for under an hour, your body's stored glycogen and a normal diet cover the energy demand. Water is usually enough, and if it's hot or you're a heavy sweater, a diluted electrolyte drink can help you feel less flat, but it's not essential for short sessions.
The picture changes for longer efforts. Once a run stretches past about 75 to 90 minutes, glycogen stores start to run low and blood glucose can drop, which is a big part of what runners describe as "hitting the wall." Taking in carbohydrate during exercise helps maintain blood glucose and delay fatigue, and the effect scales with how much and how well you can absorb it (Jeukendrup, 2014).
A single carbohydrate source, like glucose alone, tends to max out around 60 g per hour because of how the gut absorbs it. Mixing glucose and fructose uses two different absorption pathways at once, which lifts the usable ceiling to around 90 g per hour for well-trained guts (Jeukendrup, 2008). This is one of the reasons Sunday Salt's gels are built on a maple syrup base with a natural glucose to fructose split close to 50:50, rather than a single sugar source. It's a practical way to get carbohydrate in during a long run without relying on maltodextrin or refined sugar, and it's worth trialling on a training run well before you need it on race day.
What should recovery eating look like?
The hour or two after a longer or harder run is when your muscles are most receptive to refilling glycogen stores, particularly if you're training again within a day or two. Pairing carbohydrate with protein after a session supports both glycogen resynthesis and muscle repair, and getting into the habit matters more than any single "recovery window" myth (Burke, van Loon & Hawley, 2017).
Practically, this doesn't need to be a shake within fifteen minutes of finishing. A proper meal within a couple of hours, containing both carbohydrate and protein, does the job for most runners training a handful of times a week. Something like a chicken and rice bowl, a smoothie with fruit and yoghurt, or eggs on toast all tick the box. The consistency of doing this after most sessions matters more than precision on any one day.
How should runners think about hydration?
Hydration advice has swung between two extremes over the years: drink as much as possible, or restrict fluids to avoid bloating. Both are unhelpful. The clearest, most evidence-backed guidance is simpler than either: drink to thirst.
Drinking to thirst helps runners avoid both dehydration and the opposite problem, exercise-associated hyponatremia, which happens when sodium in the blood becomes diluted from drinking more fluid than the body needs (Hew-Butler et al., 2015). This matters more on longer runs and in hot conditions, where sweat losses include sodium as well as water. Replacing that sodium, alongside listening to thirst rather than a fixed drinking schedule, is a more reliable approach than forcing down water at every opportunity.
For everyday training, plain water is fine. For longer, hotter, or sweatier sessions, electrolytes become more relevant, since sweat isn't just water, it carries sodium and other minerals out with it. This is where something like Sunday Salt's Everyday or Post-Workout electrolyte formulas, made with Celtic sea salt as the sodium source, can sit alongside your normal drink bottle rather than replacing it entirely.
How does this change across a training block?
Nutrition needs shift as training volume shifts. Early in a block, when runs are shorter and easier, everyday eating and basic hydration cover most of it. As long runs stretch past 75 to 90 minutes, during-run fuelling starts to matter, and it's worth practising it the same way you'd practise pacing. In peak weeks with back-to-back sessions, recovery nutrition becomes more important because your body has less time between efforts to restock glycogen.
Race week itself is really just an extension of good everyday habits: familiar food, adequate carbohydrate, and a hydration and fuelling plan you've already tested, rather than anything new.
Frequently asked questions
Do I need special sports nutrition products to run well? No. For most runs under an hour, normal food and water are enough. Products like gels or electrolyte drinks earn their place on longer, harder, or hotter sessions where the extra carbohydrate or sodium genuinely helps.
What's the biggest nutrition mistake new runners make? Under-eating carbohydrate day to day, often because of general low-carb messaging that isn't matched to their training load. The second most common mistake is trying new foods or fuelling strategies for the first time on race day instead of practising in training.
Should I eat differently on rest days? Mostly no. Protein and overall food quality stay fairly consistent, but carbohydrate needs do drop slightly on lower-volume days, since your muscles aren't burning through glycogen the way they are on a big training day.
How much water should I drink while running? Enough to satisfy thirst, which is a more reliable guide than a fixed volume for most runners. On longer or hotter runs, replacing sodium through food or an electrolyte drink matters as much as replacing fluid.
References
- Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). American College of Sports Medicine Joint Position Statement: Nutrition and Athletic Performance. Medicine & Science in Sports & Exercise, 48(3), 543-568.
- Jeukendrup, A. E. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1), S25-S33.
- Jeukendrup, A. E. (2008). Carbohydrate feeding during exercise. European Journal of Sport Science, 8(2), 77-86.
- Burke, L. M., van Loon, L. J. C., & Hawley, J. A. (2017). Postexercise muscle glycogen resynthesis in humans. Journal of Applied Physiology, 122(5), 1055-1067.
- Hew-Butler, T., et al. (2015). Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Clinical Journal of Sport Medicine, 25(4), 303-320.
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