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Fueling for Performance

Updated: Feb 28

Katie Breazeale, MS, RD, LD

As an athlete, proper nutrition, and hydration before, during, and after exercise are critical to getting the most out of your training and on game day. Carbohydrates, protein, and fat all play different roles in fueling performance, so it’s important to ensure you’re getting enough of each. 

Before going into what to eat before, during, and after your event, it’s important to learn about macronutrients. Macronutrients, or macros, are nutrients that your body needs in large amounts for energy and optimal function.  The three macronutrients are carbohydrates, protein, and fat. Each plays a different role in fueling athletic performance, so it’s crucial to make sure your nutrition plan includes all of them.


As an athlete, carbs are number 1 in ensuring you have enough energy to complete your workout or get through a race. Most carbohydrates are broken down into glucose (sugar), which provides energy to your cells. The exception to this rule is fiber, which is not digested by humans. However, some fiber is fermented by the bacteria in your gut. Where are carbs stored in the body? The liver (100 g), muscles (400 g) and blood glucose (4 g). Depending on your muscle mass you may have higher or lower amounts. When food is fuel, carbs are a must.

The main functions of carbs include:

  • Providing instant energy. Glucose is the preferred fuel source for your brain, red blood cells, and central nervous system.

  • Storing energy. Glucose is stored as glycogen in your liver and muscles. This is particularly important for endurance athletes because it provides fuel once the glucose from your pre-workout meal is used up.

  • Keeping you feeling full. Fiber-rich carbohydrates help keep you full between meals.

  • Promoting regular bowel movements. Eating enough fiber-rich carbohydrates helps keep your bowel movements regular.

Eating enough carbs is especially important for high-intensity performance. Although protein and fat can provide the energy needed to perform physical activity, carbohydrates are the most efficiently used by the body. They are the only macronutrient that can be broken down quickly enough to supply energy during high-intensity exercise.

Carb recommendations differ based on the amount of training performed by an athlete.

For people engaged in a general fitness program, the International Society of Sports Nutrition (ISSN) recommends between 3.0 and 5.0 grams of carbs per kilogram of body weight per day.

Athletes performing moderate amounts of intense training (e.g., two to three hours per day, five to six times per week) need to consume about 5.0 to 8.0 grams of carbs per kilogram of body weight per day.

Athletes performing high-volume intense training (e.g., multiple daily workouts, five to six times per week) need to consume between 8.0 and 10.0 grams of carbs per kilogram of body weight per day.

Carbohydrate-rich foods include:


Protein is important for athletes because it’s used to repair muscles and aid in recovery. Amino acids are the building blocks of protein.

The main function of the amino acids from proteins is building and repairing. Amino acids are used to create new proteins (such as immune system cells and enzymes) in your body, as well as being used to build and repair muscle and tissues.

According to the ISSN, a daily protein intake in the range of 1.4 to 2.0 grams of protein per kilogram of body weight is recommended for building and maintaining muscle mass. There is also emerging evidence that higher protein intake of up to 3.0 grams of protein per kilogram of body weight could lead to better body composition in strength athletes.

The ISSN also provides recommendations for how much protein to eat per meal. To maximize muscle growth, it’s recommended to eat between 20 and 40 grams of protein per meal. Meals should be evenly distributed throughout the day (e.g., every three to four hours).

Protein-rich foods include:


Fats are important for athletes because they provide the body with energy and support cell function.

The main functions of fats include:

  • Storing energy. Your body’s fat stores act as an energy reserve that can be used when you’ve run out of glucose and glycogen.

  • Providing insulation to cells. Your body’s fat stores insulate and protect your organs.

  • Helping absorb fat-soluble vitamins. Fats help with the absorption of vitamins A, D, E and K.

  • Forming part of the cell membrane. The cell membrane provides protection to the cell and serves as a barrier to prevent certain molecules from getting through.

Fat- rich foods include:

The recommendations for fat intake for athletes are similar to or slightly greater than for non-athletes. The ISSN recommends that athletes consume about 30% of their daily calories from fat. If an athlete is interested in reducing their body fat, this may drop as low as 20%.

There is currently a lot of interest in using high-fat diets (such as the ketogenic diet) for athletes. However, studies looking at the effect of a high fat, low-carbohydrate diet on athletic performance and body composition have had mixed results, so more research needs to be done before we can recommend the use of high-fat diets for athletic performance.

Pre-Workout Fueling

Fueling up before a workout or a race gives you the energy to compete at your best, plus lessens your risk of injury and increases your ability to recover quickly.

It takes about four hours for carbohydrates to be digested and become part of your muscle and liver glycogen stores. Therefore, it’s best to consume your pre-exercise meal about three to four hours before exercise. Since this gives your body plenty of time to digest, include all three macronutrients (carbohydrates, protein, and fat) in the meal.

Some examples of pre-workout meals include:

  • Chicken sandwich on whole wheat bread with a side salad.

  • Egg burrito on a whole wheat wrap with avocado and a banana.

  • Grilled fish, brown rice, and roasted vegetables.

Studies also show that having a light carbohydrate and protein snack (e.g., 50 grams of carbohydrate and 5 to 10 grams of protein) about 30 to 60 minutes prior to exercise can be beneficial for performance. It’s best to choose foods that are easy to digest immediately prior to exercise.

Some examples of pre-workout snacks include:

During-Workout Fueling

Consuming carbohydrates during exercise is a way to provide an external fuel source to your muscles and central nervous system. This is particularly important for longer events, during which your glycogen stores become depleted.

If your event is longer than one hour, you will need to consume carbohydrates during your event. Studies suggest consuming between 30 and 60 grams of carbohydrates per hour at 15- to 20-minute intervals throughout the first 2.5 hours of exercise.

If your event is longer than 2.5 hours, you may need to consume up to 90 grams of carbohydrates per hour. Studies show that consuming a combination of glucose and fructose (the sugar found in fruit, fruit juices, and honey) leads to higher rates of carbohydrate absorption, so if you’re trying to hit 90 grams of carbohydrates per hour, it’s best to consume a combination of glucose and fructose.

The goal of nutrient supplementation during a race is to replace fluids that have been lost and to maintain high levels of glucose (sugar) in your blood to fuel your race.

  • Sports drink.

  • Energy gels.

  • Maltodextrin powder mixed with water (add honey to increase the amount of fructose).

It’s best to add carbohydrate consumption to your training so that your body has a chance to adapt to it. Start at the lower end (e.g., 30 grams per hour) and gradually increase to assess your tolerance. The goal is to get as close as you can to 60-90 grams (depending on how long your race is) per hour without getting digestive issues.

Post-Workout Fueling

One of the main goals of recovery between training sessions or competitions is to restore glycogen levels in the liver and muscles. Many athletes also have the goal of stimulating muscle repair and growth.

Research shows that consuming carbohydrate-rich foods that can be quickly digested, absorbed, and transported in the blood is the most effective way to replenish glycogen stores after exercise. This is particularly important if you are training on consecutive days, or even twice on the same day.

But carbohydrates aren’t the only macronutrient needed for recovery. It’s important to get enough protein after a workout or race to stimulate muscle repair and growth. In fact, a meta-analysis comparing carbohydrates paired with protein to carbohydrates only after exercise found that eating a meal containing both protein and carbohydrates was associated with better performance.

In general, it’s best if you can eat something with carbohydrates and protein within 30 minutes of completing your training or race. It’s also important to consume a high-carbohydrate meal within 2 hours of completing your training or event.

Here are some examples of easy post-workout meals:

  • Grilled chicken breast with rice and roasted vegetables.

  • Salmon with sweet potato and a side salad.

  • Cottage cheese and fruit.

  • Pita bread and hummus.

  • Tuna and crackers.

Hydration for Optimal Performance

Limiting dehydration during exercise is one of the best ways to improve performance. One of the best ways to limit dehydration during exercise is to make sure you’re drinking enough fluids before you start exercising. This means drinking enough fluids to maintain your body weight. The National Academy of Medicine recommends 9 cups of fluid per day for women and 13 cups for men, but if you’re very active, you may need more than this to maintain your weight.

You can also promote pre-exercise hydration by drinking 500 mL of water or sports drink the night before your race, followed by another 500 mL upon waking and 400 to 600 mL about 20 to 30 minutes before you start your race.

Once you’ve started exercising, you will need to drink between 0.5 to 2L per hour of fluid to offset weight loss and prevent dehydration. To do this, drink 12 to 16 ounces of cold water or sports drink every five to 15 minutes during exercise.

It’s important to note that when you’re exercising, you can’t rely on thirst to tell you when to drink. This is because, by the time you become thirsty, you’ve likely already lost a significant amount of fluid through sweat.

If you want to figure out exactly how much fluid you’re losing through sweat, weigh yourself before and after exercise. Drink three cups of water for every one pound of weight lost during exercise to promote rehydration. In addition, make sure you increase your salt intake post-exercise (such as through a sports drink or salt added to foods) to promote optimal rehydration.

Final Thoughts

When you’re training, you want to get the most out of your training so that you can perform your best on game/race day. By making sure you’re getting enough carbohydrates, protein, fat, and fluid before, during, and after, you can ensure you’re fueling yourself optimally for performance.

Need help with improving your nutrition for performance? As a registered dietitian, I’d love to help. Book an appointment today to see if I can help you!

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