Runners need more carbohydrates, more protein, and more total calories than sedentary people, and the amounts shift depending on how hard and how long you train. Getting the basics right can improve your energy, speed up recovery, and help you avoid the gut problems that plague so many runners on race day. Here’s what the evidence says about fueling for running at every level.
Daily Carbohydrate Needs by Training Load
Carbohydrates are the primary fuel for running, and your daily intake should scale directly with your training volume. Runners doing lighter or moderate training (mostly easy-paced miles) need roughly 5 to 7 grams of carbohydrate per kilogram of body weight each day. For a 70-kilogram (154-pound) runner, that works out to about 350 to 490 grams, or roughly the equivalent of several large servings of rice, pasta, bread, fruit, and potatoes spread throughout the day.
If you’re training at higher intensities or logging serious mileage, that number climbs to 8 to 10 grams per kilogram. Research on elite distance runners found that the hardest-training athletes burned through about 10 grams of carbohydrate per kilogram daily, with the vast majority of their energy coming from carbs. You don’t need to count every gram, but the takeaway is clear: harder training demands substantially more starchy and sugary foods than most people expect.
Good everyday carbohydrate sources include oats, rice, pasta, bread, potatoes, sweet potatoes, bananas, and other fruit. Spreading these across meals and snacks keeps your glycogen stores topped off between runs.
Protein for Repair and Adaptation
Running breaks down muscle tissue, and protein repairs it. A daily intake of about 1.5 grams per kilogram of body weight covers both the baseline protein your body needs and the extra demand created by training. For that same 70-kilogram runner, that’s roughly 105 grams per day, split across three or four meals.
Animal sources like chicken, fish, eggs, Greek yogurt, and dairy deliver the highest concentration of the amino acid leucine, which triggers muscle repair. Dairy proteins contain over 10% leucine, while meat and fish sit around 8 to 9%. If you eat a plant-based diet, you can absolutely meet your needs, but you’ll likely need larger servings. Most plant proteins contain 6 to 8% leucine and score lower on digestibility than animal sources. Soy is the one exception, matching animal protein in overall quality. Aiming for at least 2 grams of leucine per meal is a practical target, which might mean eating 40 to 48 grams of plant protein per sitting rather than 25 to 30 grams of whey or eggs.
Fat: Keep It Simple
Fat supports hormone production, absorbs certain vitamins, and provides fuel during lower-intensity efforts. There’s no specific gram-per-kilogram target for runners the way there is for carbs and protein. The practical approach is to let fat fill in the remaining calories after you’ve hit your carbohydrate and protein targets. Nuts, seeds, avocado, olive oil, and fatty fish are nutrient-dense choices that also deliver anti-inflammatory compounds. Most runners naturally land somewhere between 20 and 35% of total calories from fat.
What to Eat Before a Run
A carbohydrate-rich meal eaten 2 to 3 hours before running gives your body time to digest and stabilize blood sugar. Eating within that window allows insulin and glucose levels to return close to baseline before you start, which reduces the risk of a blood sugar crash in the early minutes of your run. Some people are more sensitive to this than others: if you’ve ever felt shaky or weak shortly after starting a run, eating too close to go time may be the cause.
If you only have 30 to 60 minutes, keep the meal small and easily digestible. A banana, a piece of white toast with jam, or a small bowl of low-fiber cereal works well. The goal is quick-digesting carbs without much fat, fiber, or protein, all of which slow stomach emptying and increase the chance of GI distress.
Fueling During Long Runs
For runs lasting longer than 60 to 90 minutes, your stored glycogen starts running low. Aim for 30 to 60 grams of carbohydrate per hour during these efforts. That’s roughly one to two energy gels, a few handfuls of gummy chews, or 500 to 750 milliliters of a sports drink per hour. Practice this in training, not on race day. Your gut adapts to processing fuel on the move, and what works for someone else may not work for you.
Recovery Eating After a Run
The 30 minutes immediately after a hard run are when your muscles are most receptive to restocking glycogen. Delaying carbohydrate intake by even two hours can cut the rate of glycogen replenishment in half. The well-supported ratio is 3 to 1 or 4 to 1 carbohydrate to protein, which in practice means about 1.2 to 1.5 grams of carbohydrate per kilogram plus 0.3 to 0.5 grams of protein per kilogram.
For a 70-kilogram runner, that translates to roughly 85 to 105 grams of carbs and 20 to 35 grams of protein. A large bowl of cereal with milk and a banana, or a smoothie with fruit, yogurt, and honey, hits those numbers easily. The protein doesn’t just help with muscle repair. Combined with carbohydrates, it actually enhances glycogen resynthesis beyond what carbs alone achieve. If you’re running again the next day, this matters a lot.
Carb Loading Before a Race
For races lasting 90 minutes or longer (half marathons, marathons, ultras), carb loading in the 36 to 48 hours beforehand can meaningfully boost performance. The modern protocol is straightforward: eat 10 to 12 grams of carbohydrate per kilogram of body weight per day in the one to two days before the race. For a 70-kilogram runner, that’s 700 to 840 grams of carbs daily, which is a lot of food. White rice, pasta, bread, pretzels, pancakes, juice, and jam become your best friends. You’re not trying to eat more total food. You’re shifting a larger share of your calories toward carbohydrates, which means cutting back on fat and fiber temporarily.
The old approach of depleting glycogen first through exhaustive exercise is no longer recommended. Simply increasing carb intake in the final 36 to 48 hours is enough to saturate your muscles’ fuel stores.
Iron: The Nutrient Runners Lose Fastest
Iron deficiency is one of the most common nutritional problems in runners, and it directly impairs performance by limiting your blood’s ability to carry oxygen. Runners lose iron through several pathways that sedentary people don’t: the repeated impact of footstrike destroys small numbers of red blood cells, iron is lost in sweat, and the inflammation triggered by training temporarily blocks iron absorption in the gut. Female runners face additional risk from menstrual blood loss.
When iron levels drop, the standard dietary target is about 14 milligrams of iron per day from food. Red meat, dark poultry meat, shellfish, and organ meats provide the most absorbable form. Plant sources like lentils, spinach, fortified cereals, and beans contribute iron too, but your body absorbs it less efficiently. Pairing plant-based iron sources with vitamin C (citrus, bell peppers, tomatoes) improves absorption significantly.
Foods That Cause Gut Problems
Runner’s stomach is real, and pre-run food choices are often the trigger. The most commonly avoided foods before running include dairy products, legumes, high-fiber foods like bran cereal, and meats. These take longer to digest and can cause cramping, bloating, or worse once blood flow shifts away from your gut and toward your legs.
Certain sugars are also problematic. High-fructose corn syrup, found in many energy drinks and processed foods, belongs to a group of poorly absorbed carbohydrates that pull water into the intestine and ferment rapidly. About a quarter of runners with sensitive stomachs also avoid coffee or tea before running, though caffeine tolerance varies widely. If you struggle with GI issues during runs, start by stripping your pre-run meal down to simple, low-fiber, low-fat carbohydrates and reintroduce foods one at a time to identify your triggers.
Hydration and Sodium
Sweat rates and sodium losses vary enormously between individuals. Whole-body sweat sodium concentration ranges from roughly 230 to 1,600 milligrams per liter across the athletic population. That wide range is why generic advice to “drink more water” or “take a salt tablet” falls short. A runner who loses a liter of sweat per hour with high sodium concentration has very different needs than someone sweating the same volume with dilute sweat.
A practical starting point: weigh yourself before and after a run to estimate fluid loss. Each kilogram lost corresponds to about one liter of sweat. Replace that volume gradually over the hours that follow. For runs over 60 minutes, a sports drink that contains sodium helps maintain fluid balance better than plain water. If you notice white salt streaks on your clothing or hat after running, you’re a saltier sweater and may benefit from additional sodium in your drink or food before and during longer efforts.
Beetroot Juice for Performance
Beetroot juice is one of the few legal performance supplements with solid evidence behind it. The active compound is nitrate, which your body converts into a molecule that widens blood vessels and improves how efficiently your muscles use oxygen. The effective dose is roughly 6 to 8 millimoles of nitrate, found in about 500 milliliters (two cups) of beetroot juice or a concentrated “shot.” Peak effects appear about two and a half hours after drinking it, so timing matters. Highly trained athletes may need slightly more to see a benefit, as their bodies are already operating near peak efficiency.
Plant-Based Runners
You can run at a high level on a plant-based diet, but it requires more deliberate planning. Studies lasting 8 to 12 weeks have shown that plant protein can drive the same training adaptations as animal protein, provided you’re getting enough total protein and enough leucine at each meal. Soy protein is the standout: it’s the only common plant protein that matches animal sources in digestibility and amino acid completeness. Rice protein, pea protein, and potato protein can also work, but larger doses are needed to trigger the same muscle repair response.
Beyond protein, plant-based runners should pay extra attention to iron (less absorbable from plant sources), vitamin B12 (absent from plant foods), and omega-3 fatty acids (found mainly in algae-based supplements rather than fish). A well-planned plant-based diet built around legumes, tofu, tempeh, whole grains, nuts, seeds, and plenty of fruits and vegetables covers most bases, with B12 supplementation as the non-negotiable addition.