The day before a race, your primary job is to fill your muscle glycogen stores with carbohydrate-rich, easy-to-digest foods while avoiding anything that might cause stomach trouble on race morning. For events lasting 90 minutes or longer, that means eating 10 to 12 grams of carbohydrates per kilogram of body weight over the 36 to 48 hours before the gun goes off. For shorter races, 6 to 12 grams per kilogram in the 24 hours prior is enough to top off your fuel stores.
How Much Carbohydrate You Actually Need
The numbers above sound abstract until you do the math. A 70-kilogram runner (about 154 pounds) preparing for a marathon needs roughly 700 to 840 grams of carbohydrates spread across the day before the race. That’s a lot of food: about 14 to 17 cups of cooked white rice, or the equivalent spread across pasta, bread, potatoes, and sports drinks. For a 5K or 10K, the same runner could aim for the lower end, around 420 to 840 grams, since glycogen demands are lower for races you’ll finish in under an hour.
This volume of carbohydrate is genuinely hard to eat if you’re relying on whole grains and vegetables. That’s one reason sports nutritionists recommend switching to refined, simple carbohydrates in the days before a race. White rice, plain pasta, white bread, pancakes, and pretzels are all easier to eat in large quantities and easier on your gut than their whole-grain counterparts.
What to Put on Your Plate
Think simple and bland. White rice with a little chicken, a big plate of pasta with marinara sauce, a bagel with jam, mashed potatoes, or a stack of pancakes with syrup. These are the staples of pre-race eating for a reason: they’re carbohydrate-dense, low in fiber, and unlikely to cause digestive problems.
You don’t need to eat zero protein or fat. A reasonable target is about 15% of your calories from protein, which works out to roughly 1.5 grams per kilogram of body weight. Small amounts of lean protein like chicken, eggs, or fish give your meals some staying power without slowing digestion. Fat doesn’t need a specific target on this day. Just keep it moderate, since high-fat meals take longer to clear your stomach and can contribute to nausea during the race.
Snacking throughout the day is often easier than forcing three enormous meals. Crackers, applesauce, sports drinks, fruit juice, and even gummy candy can help you hit your carbohydrate target without ever feeling uncomfortably full.
Foods to Skip the Day Before
Your goal is to keep your digestive tract as calm as possible. That means temporarily ditching many foods you’d normally consider healthy. Avoid:
- High-fiber foods: whole grains, brown rice, quinoa, bran cereals, granola, oatmeal, beans, lentils, and raw vegetables
- Gas-producing foods: broccoli, cauliflower, cabbage, onions, and dried beans
- Nuts, seeds, and dried fruit: these are high in both fiber and fat
- Spicy or heavily seasoned dishes: anything outside your normal tolerance can trigger GI distress
- Dairy (if you’re sensitive): lactose intolerance can cause cramping and diarrhea, which is the last thing you want at mile 8
Check labels on foods you might not suspect. Some yogurts, protein bars, and even drinks have added fiber. Look for products with no more than 1 to 2 grams of fiber per serving.
Does the Type of Carbohydrate Matter?
You may have heard debates about high versus low glycemic index foods before a race. Research comparing the two has found no significant difference in sprint times, endurance performance, heart rate, or perceived effort. In practical terms, this means you don’t need to stress about whether you’re eating white potatoes versus sweet potatoes or white rice versus basmati. What matters far more is total carbohydrate volume and digestive comfort. If a food sits well in your stomach and delivers carbs efficiently, it’s a good choice.
Timing Your Last Big Meal
Most runners eat their largest pre-race meal at dinner the night before. The key constraint is sleep: eating a large, carbohydrate-heavy meal less than two hours before bed can delay how quickly you fall asleep. Fat is worse, adding roughly 0.13 minutes to the time it takes to fall asleep for every additional gram consumed close to bedtime. That might sound trivial per gram, but a fatty meal can add up.
Aim to finish your last big meal at least two to three hours before you plan to sleep. If your alarm is set for 5 a.m. and you want to be asleep by 9 p.m., wrap up dinner by 7 p.m. at the latest. If you get hungry before bed, a small, low-fat snack like a plain bagel or a banana is fine and may actually help prevent you from waking up hungry in the middle of the night.
Hydration Without Overdoing It
Drink steadily throughout the day rather than chugging large volumes all at once. A practical starting point is 5 to 7 milliliters per kilogram of body weight about four hours before exercise. For a 70-kg runner, that’s roughly 350 to 490 milliliters, or about 12 to 17 ounces. If you’re not producing urine or it’s still dark after that, sip an additional 3 to 5 milliliters per kilogram over the next two hours.
Including some sodium in your fluids, whether through a sports drink or lightly salted food, helps your body retain the fluid you’re drinking. But resist the urge to drink excessively. Overhydrating in the hours before competition can dilute sodium levels in your blood, a condition called hyponatremia that causes symptoms ranging from nausea to, in extreme cases, seizures. The simplest gauge is urine color: pale yellow means you’re well hydrated.
Skip the Alcohol
Even a single drink the night before a race works against you in multiple ways. Alcohol reduces glucose availability, meaning your body has less fuel to convert into glycogen. It disrupts sleep architecture, so you wake up less rested even if you spent the same number of hours in bed. And it acts as a mild diuretic, nudging you toward dehydration at exactly the wrong time. If you’re investing the effort to carb-load and rest well, a beer or glass of wine undermines part of that work.
A Sample Pre-Race Day
For a 70-kg runner preparing for a half marathon or marathon, here’s what a day of eating might look like:
- Breakfast: Two large pancakes with maple syrup, a banana, and a glass of orange juice
- Mid-morning snack: A white bagel with honey and a sports drink
- Lunch: A large bowl of white pasta with marinara sauce, a bread roll, and diluted fruit juice
- Afternoon snack: Pretzels, applesauce, and water with electrolytes
- Dinner (finished by 7 p.m.): White rice with grilled chicken, a dinner roll, and a small serving of well-cooked carrots
- Evening snack (if needed): A plain bagel or toast with jam
This spread delivers roughly 600 to 700 grams of carbohydrate depending on portion sizes, keeps fiber low, and spaces the food out so you’re never stuffed. Adjust portions up or down based on your body weight and race distance. For a 5K or 10K, you can eat more normally and simply emphasize carbohydrates at each meal without forcing the same volume.
The Most Important Rule
Nothing new on race day applies to the day before, too. Practice your pre-race eating during training. The meal plan that works beautifully for your training partner might leave you bloated or running for a bathroom. Test your foods, your portions, and your timing during long training runs so that by race week, your routine is automatic.