Nutrition Guidelines for Endurance Training

Train smarter for your next endurance event by following these nutrition guidelines from STACK Expert Justin Groce.

Endurance Nutrition

You've trained six months for your big day. You've run hundreds of miles on asphalt and dripped sweat into your shoes for days—or you've biked far enough to loop your home state a dozen times. Mentally and physically, you are prepared for your first triathlon, marathon or other endurance event. But are you totally prepared?

If you have neglected your nutrition, your performance will suffer and you could overtrain, or, worst case, sustain an injury.

Use these basic nutrition guidelines to complete your preparation before you lace up and set a new personal record in your endurance event.


You generally need 5-7 grams of carbohydrates per kilogram of body weight during training. If you are training one to two hours per day, 5-6g/kg should suffice. For two to three hours per day, shoot for 7g/kg. Train more than that and you will need anywhere from 8-10g/kg.

You can also do "carbohydrate cycling," based on the phase of the periodization cycle you're in. When you are in low-volume periods, the amount of carbohydrates you need will be on the lower end; when you're in high-volume periods, you'll need more carbohydrates.

Before and during exercise, limit fructose (fruit sugars). They take longer to become available sources of energy and may cause gastrointestinal distress. High-fiber carbohydrates may also cause GI distress. Starchy carbs with low fiber such as pastas, rice and sweet potatoes are your best bet.

Here are some basic carbohydrate training protocols:

  • Pre-exercise meal (3-5 hours prior to training/competition): 1g/kg starchy carbohydrates with variable amount of protein
  • Pre-exercise snack (30-45 minutes prior to training/competition): 25-50g simple carbohydrates, preferably from a fast-digesting source such as glucose or maltodextrin, with a small amount of protein (5-10g)
  • Exercise nutrition: 30-60g of fast-digesting carbohydrates per hour. Your body can only oxidize a maximum of 60g/hr. These carbohydrates are not intended to fuel you—you're already fueled—but they will delay fatigue. Many athletes choose gels or 6 percent carbohydrate solutions (in my case—jelly beans)
  • Post-exercise meal (within 2 hours): 1g/kg starchy carbohydrates with a variable amount of protein

At higher altitudes, increase your carbohydrate intake by an additional 1-2g/kg. The body's metabolic rate increases with altitude, causing it to burn more calories and rely more on carbohydrates as fuel. Increase caloric consumption to maintain your weight and prevent muscle loss.


Protein is often considered less important than carbohydrates, but it's essential to muscle repair and growth. It helps offset muscle damage from competition, maintain muscle mass, optimize hormones, reduce overtraining markers and resynthesize glycogen. As glycogen levels decrease, the body uses more protein for energy.

Endurance athletes should consume 1.2-1.4 g/kg of protein at every meal. Fast-digesting proteins (whey concentrates and hydrolysates) consumed before, during, and after workouts extend time to exhaustion and improve athletic performance.

Protein timing recommendations:

  • Pre-exercise meal (3-5 hours before training/competition): 1.2-1.4g/kg
  • Pre-exercise snack (30-45 minutes before training/competition): 5-10g fast-digesting protein (whey shake) co-ingested with 25-50g of simple carbohydrates
  • During exercise: (optional) 5-10g protein or BCAAs co-ingested with 30-60g of fast-digesting carbohydrates
  • Post-exercise meal (within 2 hours)

Most athletes get enough protein in their diet. But some groups need more: younger athletes who are still growing; people on calorie-restricted diets; and vegan/vegetarian athletes.

Fats (Lipids)

Lipid is the collective term given to a wide variety of fats. Fat is critical for the reduction of inflammation, development of cellular membranes, maintenance of sex hormones (e.g., testosterone) and transport of the fat-soluble vitamins A,D,E and K.

There are two classes of fats—linolenic (omega-6) and linoleic (omega-3)—which humans must ingest through their diets, because we cannot synthesize them. Found in fatty fish and EPA and DHA in fish oils, they can decrease the risk of cardiovascular disease and increase lean body mass, as well as reduce body fat and salivary cortisol. 
A novel approach to fat consumption for athletes is to consume about 1g/kg of body weight per day.

Read more:


  • Antonio et al (2008). Essentials of Sports Nutrition and Supplements. Totowa, NJ: Humana Press.
  • Benardot, D. (2006). Advanced Sports Nutrition. Champaign, IL: Human Kinetics.
  • Gilbala, M. (2002). "Dietary protein, amino acid supplements, and recovery from exercise." GSSI Sports Science Exchange, 87, 15(4).
  • Burke, L. & Coyle, E. (2004). "Nutrition for athletes." Journal of Sports Sciences, 22(1): 39-55.
  • Jeukendrup, A. (2007). "Carbohydrate supplementation during exercise: Does it help? How much is too much? GSSI Sports Science Exchange, 106, 20(3).
  • van Loon, L. (2013). "Is there a need for protein ingestion during exercise?" GSSI Sports Science Exchange, 26(109).
  • Trumbo et al (2002). "Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein and amino acids." Journal of the American Dietetic Association, 102(11).
  • Noreen et al (2010). "Effects of supplemental fish oil on resting metabolic rate, body composition, and salivary cortisol in healthy adults." Journal of the International Society of Sports Nutrition, 7(31).

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