The week before a half marathon, your diet should gradually shift toward more carbohydrates, less fiber, and familiar foods that you know sit well in your stomach. The goal is to top off your glycogen stores (the fuel your muscles burn during the race) while avoiding anything that might cause digestive trouble on race morning. Here’s how to structure each phase of the week.
Early in the Week: Days 7 Through 4
This part of the week doesn’t require dramatic changes. You’re tapering your training, so your calorie needs are dropping slightly, but you don’t need to cut portions. Focus on eating balanced meals with a mix of carbohydrates, protein, and healthy fats. Think pasta with chicken, rice bowls, sandwiches on regular bread, oatmeal with fruit.
The most important rule for this stretch is to avoid experimenting. Don’t try a new restaurant, a new cuisine, or a food you haven’t eaten during training. Your gut adapts to what it knows, and introducing something unfamiliar this close to race day is an unnecessary gamble. If you’ve been eating the same rotation of dinners for months, stick with it.
Protein matters more than runners sometimes realize during a taper. Aim for roughly 1.2 to 1.8 grams per kilogram of body weight each day, spread across your meals. For a 150-pound runner, that’s about 80 to 120 grams. This supports muscle repair from your final training sessions and helps you feel satisfied even as your activity level dips.
Carb Loading: Days 3 Through 1
True carbohydrate loading begins about 36 to 48 hours before the race. For events lasting longer than 90 minutes (which a half marathon is for most runners), sports nutrition guidelines recommend 10 to 12 grams of carbohydrate per kilogram of body weight per day during this window. For a 150-pound (68 kg) runner, that works out to roughly 680 to 816 grams of carbs daily. That’s a lot of pasta.
In practice, many half marathon runners don’t need to hit the extreme end of that range, since it was developed primarily for marathon and ultra-distance athletes. A more realistic target is 7 to 10 grams per kilogram, which still gives your muscles a full tank without forcing you to eat uncomfortably large volumes of food. Prioritize calorie-dense carb sources: white rice, white bread, bagels, pancakes, pretzels, fruit juice, and pasta with simple sauces. These pack in carbohydrates without filling you up with bulk.
As you increase carbs, you’ll naturally crowd out some fat and protein. That’s fine for a couple of days. You’re not trying to eat more total food; you’re shifting the ratio. Swap the side salad for a second roll, choose jam over peanut butter, and pick leaner proteins so there’s room on your plate for more starchy foods.
Expect the scale to go up 2 to 4 pounds. Every gram of stored glycogen holds roughly 3 grams of water alongside it, so gaining a couple of pounds of water weight is actually a sign that the loading is working. That water becomes available during the race, which is a good thing.
Cutting Fiber and Problem Foods
In the final 24 to 48 hours before the race, trim your fiber intake noticeably. Fiber draws water into your digestive system, which can cause bloating, gas, nausea, or diarrhea mid-run. Foods to pull back on include:
- Beans and lentils
- High-fiber cereals and granola
- Nuts and seeds
- Dried fruits
- Raw vegetables in large quantities
- Whole grain bread (switch to white)
This is also the time to avoid spicy and heavily seasoned foods. Spicy curries, hot peppers, garlic-heavy dishes, onions, chili, and acidic sauces like salsa or vinegar-based dressings can all irritate the stomach lining and trigger acid reflux or indigestion. Keep your meals bland and familiar.
Other common triggers to skip in the last two days: rich dairy (especially if you’re even mildly sensitive), fried or greasy foods, alcohol, and large amounts of caffeine beyond your normal intake. Your race-eve dinner should be the most boring, predictable meal of the week. White rice with a simple lean protein and a mild sauce is the classic choice for a reason.
Hydration Through the Week
Aim for at least 3 liters of water daily during race week, more if you’re training in heat. You don’t need to dramatically overdrink. Just stay consistently hydrated rather than trying to catch up the night before. The day before the race, target 2 to 3 liters and skip alcohol entirely.
You may have heard that loading up on sodium or salt tablets prevents cramping. The scientific evidence doesn’t actually support a link between sodium depletion and exercise-related muscle cramps. Drinking excessive fluids combined with extra sodium before a race can, in extreme cases, lead to dangerously low blood sodium levels. A better approach: salt your food normally, drink to thirst, and don’t overthink it. If you sweat heavily and have found electrolyte drinks helpful in training, continue using them at the same level you’re accustomed to.
Race Morning Breakfast
Eat your last substantial meal 2 to 3 hours before the starting gun. This gives your body enough time to digest without leaving you running on empty. A good target is a high-carbohydrate meal in the range of 200 to 400 calories, with moderate protein, low fiber, and minimal fat. A white bagel with a thin layer of peanut butter and banana, a bowl of white rice with a little honey, or plain toast with jam and a small amount of eggs all work well.
The closer you get to race time, the simpler your food should be. If you eat something in the final hour before the start, keep it to low-fiber, mostly simple carbohydrates: a few sips of sports drink, a gel, or a handful of pretzels. The idea is to get fuel into your bloodstream quickly without leaving undigested food sitting in your stomach when you start running.
Whatever you choose for race morning, practice it during training. Your pre-race breakfast should be something you’ve eaten before a long run at least two or three times. Race day is not the time to discover that a particular brand of energy bar doesn’t agree with you.
A Sample Day-by-Day Framework
Here’s a practical outline pulling everything together:
- Days 7 to 4: Eat your normal balanced diet. Keep protein steady at 1.2 to 1.8 g/kg. Stay hydrated. No new foods.
- Days 3 to 2: Begin shifting meals toward more carbohydrates (7 to 10 g/kg per day). Start reducing fiber, raw vegetables, and heavy fats. Choose white grains over whole grains. Keep meals familiar.
- Day 1 (race eve): Highest carb intake. Very low fiber and fat. Bland, simple dinner. No alcohol. 2 to 3 liters of water through the day.
- Race morning: High-carb, low-fiber breakfast 2 to 3 hours before the start (200 to 400 calories). Only simple carbs in the final hour.
The weight you gain from carb loading, the blandness of your meals, and the temporary shift away from vegetables can feel strange after months of balanced training nutrition. That discomfort is normal. You’re not eating this way permanently. You’re giving your body the best possible fuel tank for 13.1 miles.