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What diet to prioritize before, during, and after a trail or ultra-trail?

August 2023 - Reading time: 9 minutes

It is not always easy to know how to best fuel yourself before, during, and after a race. If you ask five runners, you’ll probably get five different answers. To find out what really works for your body, you need to get out there and experiment.


The Basics of Running Nutrition

How much food should you eat during a run? The quick answer is if you’re going for a one-hour run or less, you can probably get by with just drinking water. If you’re running for an hour or more, it’s time to start eating at a rate of about 200 to 300 calories per hour. For most runners, this means eating and/or drinking 80 to 100 calories every 20 to 30 minutes, mostly in the form of small carbohydrate-rich snacks like gels, energy bars, and sports drinks.
The exact number of calories depends on several factors, including the length and intensity of your run and your body size. A larger person will likely need more calories per hour than a smaller person. Similarly, someone running a very intense race will need more calories per hour than someone running a short, easy race.
The quality of the calories, meaning the type of food you consume, is also essential: Carbohydrates are the main source of energy during a run, while proteins and fats are better before and after the run.

The Role of Carbohydrates

When you run long distances, your body first uses glycogen as its main fuel. Glycogen is stored in the muscles and liver to provide efficient and easily accessible energy.

Glycogen comes from consuming carbohydrates. That’s why you’ve probably heard of athletes carbo-loading the night before a big race. Eating a lot of carbohydrates like pasta, bread, or potatoes helps fill your glycogen stores and start your race with a full tank of energy.

During the run, your body burns glycogen quite quickly (it can be depleted in a few hours). So you need to replenish your glycogen stores by snacking mid-run on items like energy bars and gels that contain carbohydrates. If you run out of glycogen, you may experience what athletes call "bonking" or "hitting the wall," where you feel really bad and tired.

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The Role of Proteins and Fats

Fat is an essential energy source for your body, but it takes some time to be converted into fuel. This means you can’t eat a high-fat meal just before a run and expect those fats to carry you through. To have your energy reserves ready for the long term, make sure your daily diet includes fats.

Some runners choose to eat a bit of fat during their run, especially on multi-hour outings. This can relieve your taste buds from the monotony of energy gels and help you feel fuller. Adding solid foods such as bars, wafers, or peanut butter sandwiches can be a welcome change. But don’t overdo it. Fats take longer to break down than carbs, which can make you feel too full and cause stomach issues during your run.

Proteins are not a primary energy source and generally aren’t a significant component of mid-run nutrition plans. But they should be part of your daily diet and post-run recovery plan.

When you run, your body breaks down muscles. Proteins are ideal for helping your body rebuild tissues and recover after endurance activities. Therefore, after a long run, have a healthy meal containing carbs and proteins within about 1 to 2 hours. It’s sometimes recommended that athletes take in proteins more quickly (within 30 minutes after finishing the run) to maximize recovery, but the current general consensus is there’s no rush if you plan to eat within the next 1 to 2 hours.

Eating small amounts of protein during a long run can be acceptable and may help speed up recovery once the run is over, but limit your intake to about 15g per hour - beyond that, you may feel full and uncomfortable.

Developing a Nutrition Plan

Since every runner is different, it’s hard to dictate a strict eating plan, but there are some reliable guidelines to get you started. Experiment with foods during training runs to see what works best for you. And never forget: Despite what you’re told, if it works for you, keep doing it.

What to Eat the Day Before a Long Run?

The day before a long run (lasting about an hour or more), have a healthy meal rich in fats, proteins, and carbs but low in fiber. The fats you consume should be healthy fats from foods like avocados and extra virgin olive oil. Healthy fats are beneficial for heart health, immune system function, joint health, recovery, and injury prevention. Don’t overdo it and eat a huge meal that will leave you feeling full the next morning. Also, avoid foods that might cause you problems. For example, if spicy foods upset your stomach, avoid them.

What to Eat Right Before a Long Run?

About 2 to 3 hours before a long run, it’s advisable to have a preparation meal mainly composed of carbohydrates. Add some proteins to help you feel full during the run, but don’t eat too many fats or fibers, as they can make you feel too full and have you rushing to the bathroom.

Granola with berries, a bagel with peanut butter, or oatmeal with dried fruits or bananas are good ideas. Generally, aim for a meal of about 400 to 600 calories. It’s important to give your body time to digest your pre-run meal, which is why we recommend eating 2 to 3 hours before. If your last meal was more than 3 hours ago, try to have a light snack about 30 minutes before starting your run.

What to Eat During the Run?

For runs less than an hour: Most people can get by with just drinking water and not eating - your body should have enough glycogen stored to get you through.

For runs longer than an hour: Adopt a nutrition strategy that keeps you energized and helps with recovery. For most runners, this means bringing carbohydrate-rich snacks, like energy gels, energy bars, and fruits. Here are some general tips:
Most runners will want to limit their carbohydrate intake to 30-60 grams per hour. 60 grams per hour is the maximum amount most people’s bodies can absorb, consuming more could cause stomach upset.
The goal is to consume between 200 and 300 calories per hour. Knowing that one gram of carbohydrates equals 4 calories, don’t exceed 240 calories of carbohydrates per hour. (Metabolism varies slightly from person to person, which is why we recommend a range of 200 to 300 calories).

For runs lasting several hours: Consider incorporating fats to help you feel full while changing from gels. Energy bars, nuts, beef jerky, and protein sandwiches can be good choices. Also, listen to your cravings. Your body surprisingly knows how to tell you what it needs. If you regularly do long endurance runs, a small amount of protein (about 15g per hour) can help speed up your recovery.
Remember to aim for an intake of 200 to 300 calories per hour. Many pre-packaged gels, bars, and energy chews come in portion sizes that make this easier.

What to Eat After the Run?

After a short run of less than 45 minutes, what you eat isn’t very important. But after a long and strenuous run, plan to eat foods rich in carbohydrates and proteins within 1 to 2 hours after finishing your run, to replenish your glycogen stores, replace lost electrolytes, and rebuild muscles that were broken down during your run. Some runners like to drink a recovery drink containing a mix of proteins, carbs, fats, and electrolytes. A healthy meal with good nutritious ingredients works just as well.

Remember to stay hydrated: Drink water to rehydrate. An electrolyte replacement drink isn’t necessary if you’re eating. There’s nothing wrong with celebrating a great run with a beer, but go easy. Alcohol is a diuretic, which means it can pull fluids from your body and worsen your dehydration.


Pay attention to your daily diet: It’s not every day you need to fuel up for a long run or big competition. As an athlete, it’s important to consider the amount of carbs, proteins, and fats in your daily diet. A healthy, balanced diet made up mainly of carbs, followed by fats and proteins, will help keep you energized.

Experiment: To find out what foods work for your body when you run, you need to experiment. Some lucky runners can tolerate all foods, but many others find that the jostling of running causes nausea and irritation. If you experience stomach discomfort, check food labels and try to avoid common allergens such as whey, gluten, or soy. You can also try cutting out solid foods and see how sports drinks, shakes, and homemade smoothies work.

Experiment with different combinations of foods and amounts before, during, and after your training runs to determine what works and what doesn’t. Keeping a journal to note what you eat and when can be helpful.

Drink your calories: If you know that solid foods irritate your stomach when you run, try fueling in liquid form. Many sports drinks contain calories in the form of carbs, fats, and proteins. However, be careful not to overdo it and combine an energy drink with an energy food - too many carbs can cause stomach upset. If you use gels, energy bars, or chews to fuel yourself, follow a bite with a sip of plain water rather than a sports drink.

On race day, don’t suddenly try something new. It can be tempting to gulp down the treats offered at aid stations, but if you don’t know if the chocolate bars, sodas, or anything else offered works for you, don’t consume them. You’ve developed a plan, so stick to it.

Set a timer: It’s easy to zone out during a long run and lose track of the last time you took a sip of water or an energy gel. Many runners like to set a timer on their watch to beep every 20 to 30 minutes to remind them to eat and/or drink 80 to 100 calories.

Nicolas Dayez from Athlé Expliqué

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