Essential Guide to Running Nutrition

Lori Nedescu, MS RD CSSD
by Lori Nedescu, MS RD CSSD
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Essential Guide to Running Nutrition

Putting in the miles makes a person a runner, but fueling your body well can turn a middle-pack runner into a great runner. Proper nutrition provides your body with the energy to go the distance, improves body composition, aids injury prevention and reduces mid-run stomach issues. This guide provides the nutrition knowledge to fuel your running needs.

When it comes to fueling to support running fitness, it comes down to a few simple things:

  1. Eating to support good general health
  2. Consuming enough carbohydrates for energy production
  3. Nutrient timing


As a runner, your body needs the same three macronutrientscarbohydrates, fat and protein — as anyone else, but in slightly different amounts. Each of these macros relates to runner’s needs increased needs slightly beyond the basics of the general population.

  • Dietary protein is required for muscles to take on the daily demands of running without becoming worn down.
  • Fat intake provides energy for long efforts that are performed at a lower intensity. At more calories per gram (9 calories/gram versus 4 calories/gram for carbs and protein), consuming fat helps runners meet high-calorie needs from smaller portions of food. Even runners looking to lose weight, may have greater overall energy needs to support normal body functions and running performance.
  • Carbohydrates are the ultimate macronutrient for most runners because an active body prefers carbohydrates as a fuel source for intense athletic performances. Without enough carbohydrates, the body breaks down protein which leaves you depleted. This ends up stalling performance and increases the risk of injury and poor health.

Beyond macronutrients and overall calories, runners need to make sure they are getting micronutrients like vitamins, minerals and phytonutrients from a variety of whole foods to support good health functions, proper recovery and energy metabolism.


Carbs outshine the other macronutrients when it comes to running because carbs are the most efficient fuel source for your metabolism to process and turn into usable energy for intense training.

Most runners are familiar with the concept of increasing carbohydrates prior to a big run or race. The purpose of this is to load the body with maximum energy stores for ultimate performance. Informing yourself on the details of a carb load can help you achieve a PR. The simple protocol is to consume 10–12 grams of carbohydrates per kilogram of body weight for 48 hours leading up to the target event.

Runners should choose carbohydrates from a variety of healthy foods to promote lean body mass, good health and energy needs. Carbohydrate sources include dairy products, pastas, cereals, oats, bread products, vegetables, fruit, sweet beverages, candies and processed sport foods. Runners should try to rely primarily on complex, less processed carbohydrate sources and use refined options such as sport gels, bars, drinks and chews to support training when necessary.


There are two main categories of carbohydrates: complex and simple. Neither are necessarily healthy or unhealthy, as both types are valuable to runners.

Complex carbohydrates are carbohydrate sources that contain more fiber and therefore are digested at a slower rate, helping you feel fuller for longer and supply long-term energy. These carbs are great for health, digestion and satiety, but they might cause gastrointestinal issues if consumed just before a run.

Examples of complex carbohydrates: corn, quinoa, oatmeal, bran, beans, legumes, barley, fruit and vegetables.

Simple carbohydrates are found in foods that are easier for your body to break down quickly and provide immediate energy. These types of carbs are better tolerated before runs to boost the body’s energy supply while being easy on the GI system. Simple carbohydrates encompass a large variety of foods including whole, nutrient-rich foods such as milk (even plant milks) and breads as well as nutrient-lacking foods like soda and sport gels. Both types can fit into a runner’s diet, but the simplest of simple carbs — sugar — should be reserved for helping to boost immediate performance demands and limited outside of athletic training.

Examples of simple carbohydrates include fruit/vegetable juices, soda/sweetened beverages, sport gels, milk, oat or rice milk, energy drinks, table sugar, maple syrup and candy.


Carbohydrates consumed from dietary sources are broken down into smaller sugar units called glucose. Glucose molecules are transported through the bloodstream to be used as energy for internal biological processes in the brain and body plus extra needs, such as running.

When carbohydrate intake exceeds the needs of your body, glucose is stored as glycogen in the liver and muscles. This stored glycogen is essential for times when the body requires more energy than is supplied in the bloodstream by immediately available glucose, an example of this is in exercise. The liver can store roughly 100 grams or 400 calories of carbohydrates and muscles can store roughly 500 grams or 2,000 calories of carbohydrates. This is why you can perform some exercise without taking in a source of carbohydrates, however the goal is to have energy to spare, not completely deplete your body, which can lead to dizziness, weakness, irritability and fatigue (otherwise known as bonking). Because carbohydrates are stored in muscles, glycogen is very accessible for, and efficiently utilized, in the ATP-making process. Compared with fat and protein, carbohydrates are metabolically more efficient at creating intracellular energy to fuel intense energy needs such as hard runs.

When your muscles, liver and bloodstream are maxed out, additional carbohydrate intake is stored as fat. The amount of carbohydrates required is based on body weight and the amount of training being completed. One who trains a light-to-moderate amount needs roughly 5g of carbohydrates per kilogram of body weight each day while a high-volume runner might need up to 12g/kg/day. Simply put, those who train more hours a day need a higher percentage of their overall calories to come from carbohydrates.


Simply put, eating certain foods at certain times improves your body’s ability to process energy efficiently, leading to better performance, recovery and body composition.


Normal intake refers to the general, overall diet a runner consumes away from the sport-specific before, during and after workout fuel. This includes balanced meals full of fiber, vitamins, nutrients, fat, protein and complex carbohydrates from colorful, less processed foods.

Meals furthest from the run should be the most complex and bulky to provide the runner with good nutrition and promote healthy body composition without compromising running performance. This general diet makes up 70–80% of your calories, so it should take priority! To get the most out of your athletic goals, supplement this intake with additional workout-targeted fuel to support each of your runs.


Eating before training serves two important purposes:

  1. Keeping you from becoming hungry during the workout and
  2. Providing muscle and mental energy

Runners can benefit from 200–300 calories from easily digested carbohydrate sources consumed 2–3 hours prior to training. Another 30–60 grams just before the workout can help top off energy stores. Exactly how much and when to eat depends on the training at hand and the runner’s digestive tolerance. Fluids should also be consumed before training with the goal of preventing water losses during the activity.


The purpose of fueling during a run is to provide energy to muscles in need. This is most important for runs lasting around 90 minutes or longer to prevent fatigue as stored energy is used. Shorter runs can also benefit from fuel to improve digestive tolerance and provide immediate energy to hard efforts. Carbohydrates are the preferred source of fuel at a rate of 30–90 grams per hour. See what this amount looks like.

Ultra runners might add mixed macronutrients to prevent tissue breakdown and hunger during multi-hour runs. Liquids should also be consumed to assist the digestive process and prevent dehydration. Runners should consume sips throughout training as tolerated, starting early and not relying on thirst, which is a poor indicator of needs. Electrolytes may be helpful for runners in hot, humid conditions or those who are prone to cramping in order to promote proper nerve-muscle function.


A combination of protein and carbohydrates is advised immediately (within 30 minutes) after finishing a run to help with the rapid replenishment of muscle energy. This is known as the window of opportunity. A simple cup of chocolate milk is sufficient. Athletes needing this rapid replenishment include those with multiple workouts within 24 hours. Runners who struggle with a large appetite hours after running should take advantage of the post-run snack to help restore energy balance and lessen cravings. Fluids should be replenished after a hard run. In most cases, water is sufficient.


How to avoid GI issues is a topic very important to runners of all levels and distances. During exercise, blood flow to the gastric system is slowed to prioritize blood flow to muscles in need. This means digestion is practically stopped. If you ate a large or bulky pre-run meal, this process can leave you feeling heavy and nauseous throughout your training.

Running is a sport that causes the stomach to be jostled around, which can lead to increased digestive issues mid-run when compared to other sports, such as cycling, where the stomach stays in relatively the same position. The amount and type of carbohydrates consumed can hurt or help, but it’s highly individual.

Runners should feel confident they can ‘train the gut’ just like they train their legs and lungs to handle harder, longer running. Start with small portions of simple, easy to digest carbohydrates before and during training such as a banana and toast an hour before with a sport drink consumed throughout the effort. This protocol should advance to foods that provide more energy and nutrition as needs, tolerance and training progress.

For example, a gut-trained runner might consume a bowl of oatmeal with a banana and maple syrup two hours prior, top off with a banana 30 minutes before, and consume water with sport gels throughout the run. An interesting study showed consuming raisins versus sport gels provided the same performance effect, it simply comes down to what the athlete can tolerate that is the make or break factor.


Mastering the basics of a good diet combined with proper carbohydrate supplementation appropriate for exercise demands is key for any runner looking to perform well. Of course, there are many steps beyond these basics that advanced athletes can explore to boost performance, body composition and health outcomes. Diet quality, antioxidants, omega fatty acid profile, fiber, dietary nitrates (beets, greens) and pro/prebiotics are all next step nutrition options to advance an individual’s general food intake.

For runners looking to take their fueling to the next level or get assistance mastering the basics, a one on one consultation with a board certified sport dietitian (CSSD) and experience as a runner is invaluable.

About the Author

Lori Nedescu, MS RD CSSD
Lori Nedescu, MS RD CSSD

Lori, MS RD CSSD is an accomplished sports dietitian; she holds a Master’s Degree in Human Nutrition and Certification as a Specialist in Sports Nutrition. As a current professional road cyclist and previous elite marathoner and ultra-runner, Lori knows firsthand that food can enhance or diminish performance gains. She understands the importance of balancing a quality whole food based diet with science-backed performance nutrition and strives to share this message with others. Learn more about her @HungryForResults.


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