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Marathon race week nutrition: a day-by-day timeline

What to eat and drink from a week out to the finish line, plus how a triathlon week differs. · 8 min read · Updated October 24, 2026

Key takeaways

How we made this guide: we built it from the research below and checked every number against it: ACSM, Academy of Nutrition and Dietetics & Dietitians of Canada joint position stand (2016); Burke et al., carbohydrates for training and competition (2011); Jeukendrup, nutrition for endurance sports (2011); Bussau et al., carbohydrate loading (2002); Rapoport, metabolic factors in marathon runners (2010); Tarnopolsky et al., carbohydrate loading in men and women (1995); Fernández-Elías et al., muscle water and glycogen (2015); Bosquet et al., tapering meta-analysis (2007); Pfeiffer et al., intake and stomach problems in endurance events (2012); Wilson, stomach distress in a half-Ironman (2016); IOC consensus on dietary supplements (2018); ISSN position stand on caffeine (2021); Montero-Carrasco et al., diets and stomach symptoms in endurance athletes (2024).

This guide is for runners and triathletes who want one clear plan for the last week before a marathon or longer race. Glycogen is the carbohydrate your muscles and liver store as fuel. g/kg means grams per kilogram of body weight; 1 kg is 2.2 lb, so a 150 lb runner is about 68 kg. Running low on glycogen is what runners call hitting the wall, and a modeling study of marathon physiology reports that more than 40% of marathoners say they hit it (Rapoport, 2010).

The week at a glance

WhenWhat to doExample: 68 kg runner
7 to 3 days outEat normally for your training. Keep carbs at every meal.Your usual meals
2 days out through the day beforeRaces over ~90 min: 10–12 g/kg of carbs a day (see the carb-loading guide). Shorter races: a normal carb-rich day.~680–820 g of carbs a day
The night beforeA familiar, low-fat, carb-based dinner, sized like a normal dinner.One dinner inside that day’s total
Race morning1–4 g/kg of carbs, 1–4 hours before the start (see race-morning breakfast). Optional caffeine: 3–6 mg/kg about 60 min before.~68–272 g of carbs; ~200–400 mg of caffeine
During the race1–2.5 h: 30–60 g/hour. Past 2.5–3 h: up to 90 g/hour if practiced (see carbs per hour).4-hour marathon: ~240–360 g (60–90 g/hour)
AfterA real meal with carbs and protein within about two hours (see after a long run).A meal with ~15–25 g of protein

What should you eat from seven to three days out?

Eat the way you do on a normal training day, with carbs at every meal. Your mileage falls in these days because of the taper. A meta-analysis of 27 studies found the best results from tapers of about two weeks that cut training volume by 41–60% while leaving intensity and frequency alone (Bosquet et al., 2007). So you are still running, just less.

Your appetite may drop along with your mileage, which is fine. Don’t cut carbs, though; the next two days ask for a lot of them. If you feel overfull, we’d trim fat and extras first (our rule of thumb, not a finding from the studies).

When does carb loading start, and how much do you need?

The joint position stand sets the loading target for events with more than 90 minutes of sustained or intermittent exercise: 36–48 hours at 10–12 g/kg of carbohydrate per 24 hours (Thomas, Erdman & Burke, 2016). Count back from your start time. For a Sunday morning race, you begin Friday morning and eat that way through Saturday. For shorter events, the same stand lists 7–12 g/kg a day, its range for daily fuel needs, with no special loading.

For a 68 kg runner, 10–12 g/kg is about 680–820 g of carbs a day. At roughly 4 calories per gram, that is about 2,700–3,300 calories from carbs alone, which can match or beat a normal day’s total food. Fat and extras have to shrink to make room.

Why 36–48 hours? The stand notes that an easier training day plus 7–12 g/kg can restore normal muscle glycogen in about 24 hours, and stretching it to 48 hours can push it above normal. In a small study of eight trained men who rested and ate 10 g/kg a day, muscle glycogen rose from about 95 to 180 mmol per kg within the first day and then stayed level (Bussau et al., 2002). That suggests rest and food do most of the work early, so there is no need to start sooner than two days out.

Two caveats. In a small study of seven men and eight women, moving to 75% of calories from carbohydrate for four days raised muscle glycogen by 41% in the men and not in the women (Tarnopolsky et al., 1995). One study can’t settle the question, but it is one reason the stand’s target, and ours, is in grams per kg rather than a percentage of calories. And one review notes that high starting glycogen doesn’t have to come from traditional loading, if your plan also fuels well during the race (Jeukendrup, 2011). For a marathon or longer, we’d still follow the standard target.

How do you carb load without feeling bloated?

Expect the scale to rise. Each gram of glycogen is stored in muscle with at least 3 grams of water (Fernández-Elías et al., 2015), so a heavier number on race morning is likely stored fuel and the water that goes with it, not a reason to cut carbs.

What should you eat the night before?

Eat a dinner you already know, sized like a normal dinner, built on carbs and light on fat and fiber. The stand says choices high in fat, protein or fiber may need to be avoided to lower the risk of stomach problems. If you are loading, dinner is one meal of the day’s total; the snacks and drinks earlier in the day carry the rest.

Sip fluids through the evening, enough for pale-yellow urine, but don’t force extra water. Over-drinking in the hours and days before an event is a recognized contributor to hyponatremia, a dangerous drop in blood sodium (Thomas et al., 2016).

What should you eat and drink on race morning?

The stand’s target is 1–4 g/kg of carbohydrate, eaten 1–4 hours before exercise lasting more than an hour. After an overnight fast, liver glycogen is low, and this meal helps top it up. For a 68 kg runner the range is about 68–272 g. A way to apply it (ours, not the stand’s): eat near the low end if the start is an hour or two away, and nearer the high end if you can eat three or four hours before. Low-fat, low-fiber, lower-protein foods tend to sit best.

Go gently if your stomach’s sensitive. Among 53 half-Ironman triathletes, higher race-morning calories and carbs were modestly linked to upper-stomach symptoms on the bike, and a history of stomach trouble was the only non-diet factor linked to symptoms (Wilson, 2016). If that sounds like you, start lower and rehearse in training.

Fluids. The stand suggests about 5–10 mL per kg in the 2–4 hours before exercise, enough for pale-yellow urine: roughly 340–680 mL (11–23 oz) for 68 kg. Sodium in your food or drink helps your body hold on to the fluid.

Caffeine (optional). The IOC consensus and the ISSN position stand both put the studied dose at 3–6 mg per kg, about 60 minutes before the start (Maughan et al., 2018; Guest et al., 2021), or roughly 200–400 mg for 68 kg. Doses near 9 mg/kg haven’t been shown to add benefit and bring more side effects such as nausea and anxiety. If you don’t usually have caffeine, race day is a poor time to learn how you react. In the half-Ironman study above, morning caffeine was also modestly linked to lower-gut symptoms during the run. Try our caffeine calculator.

How much should you eat during the race?

The stand’s schedule: nothing needed under 45 minutes, and small amounts (even a mouth rinse) at 45–75 minutes. From one to 2.5 hours, aim for 30–60 g of carbs an hour. Past 2.5–3 hours, up to 90 g an hour, using products that blend glucose and fructose, which the gut can absorb more of (Thomas et al., 2016; Burke et al., 2011). “Up to” matters: 90 g an hour is a ceiling for runners who have trained their gut, not a race-day goal.

A four-hour marathon is past that 2.5–3 hour line, so up to 90 g an hour applies: 360 g at most. Our fueling plan uses 60 g an hour as a practical floor for races that long (our rule of thumb, not the stand’s), which comes to about 240 g. In a survey of 221 endurance athletes, marathon runners reported averaging 35 g an hour (Pfeiffer et al., 2012). Our marathon fueling plan builds this out by finish time.

How much should you drink, and do you need sodium?

Sweat rates range from about 0.3 to 2.4 liters an hour, so there is no single right number. The stand’s goal is to keep fluid loss under 2% of body weight, and its typical range is 0.4–0.8 L an hour (about 14–27 oz), adjusted to you. Over-drinking is the main cause of hyponatremia and is more common in recreational runners, and thirst is usually a good signal for when to drink.

The stand says to take in sodium during exercise if you sweat more than about 1.2 L an hour, have salty sweat, or race longer than two hours, which covers most marathon finishers. To learn your rate, weigh yourself before and after a long run; a kilogram lost is about a liter of sweat. Our sweat-rate calculator does the math.

How is race week different for a triathlon than a marathon?

The shape of the week is the same: taper, load, familiar meals. The differences come from how long you will be out there and how you can eat on the course.

How do you track race week without obsessing?

You don’t need to weigh every bite. Three things are worth a rough record: your carb total on loading days, what you ate before your last good long run, and how your stomach felt. We built My Track Record so logging a meal is one spoken sentence, and we estimate the carbs as a range. You can set a daily carbs goal in grams and see the day’s total against it. Treat the totals as close estimates, not exact grams, and once you are in the right neighborhood, stop checking.

Log your loading days in one sentence.
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What should you eat after the race?

Within about two hours, eat a real meal with carbs and protein. The stand’s protein target for early recovery is 0.25–0.3 g/kg, or 15–25 g. If you have another demanding session within eight hours, it lists 1–1.2 g/kg of carbs an hour for the first four hours. Replace fluid too: about 1.25–1.5 L for every kilogram lost, with some sodium to help you hold it. More in our after-a-long-run guide.

The rule that covers all of it: nothing new in race week. No new foods, drinks or breakfasts. Everything here should be something you have already done before a long run.

Andrew, founder of My Track RecordBy Andrew, founder of My Track Record. Andrew has been active all of his life across a variety of sports and continues to stay active through climbing, swimming, weight training, golfing, snowboarding, and more. He built My Track Record so logging food and training takes one spoken sentence and can support any activity. He puts these guides together from published sports science research cited on each page. About Andrew

Sources

General information for healthy adult runners and triathletes, not medical advice. If you have a medical condition, are pregnant, or have a history of disordered eating, talk to a doctor or registered dietitian before changing how you eat or use caffeine.

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