Nutrition for Endurance Athletes

  • Evie Katahdin, ND, MSOM, LAC

It is especially important for endurance athletes to adopt a whole foods, varied and healthy diet. Your body is regularly pushed beyond normal limits, and you have high expectations for both strength and speed. Short bursts of energy are easier to come by than the energy required for hours of training for distance events. It is essential that you take your health seriously and give your body what it needs in order to ask, in turn, for your two hour run on Sunday morning.


  • Stored in the liver and skeletal muscle as glycogen
  • Glycogen is readily available for use as energy for exercise
  • High glycemic index carbohydrates are simple sugars, useful immediately before, during and sometimes following exertion to establish and maintain muscle glycogen
  • Low glycemic index carbohydrates are complex carbohydrates such as whole grains and should be consumed as part of your normal daily diet
  • In general, a serving of carbohydrate should be about the size of your fist but round up during periods of intense training

Glycogen is broken down into glucose for energy, but your stores are limited. If you exercise more than once in a 24 hour period you must replenish immediately after exercise to be able to sustain the next bout of work without depleting lean muscle mass. If you work out just once per day, your daily intake of complex carbohydrates will be adequate to replenish what was used in training.

Without adequate daily carbohydrates, athletes will suffer from excessive fatigue, sluggishness, sensation of heavy legs and an inability to maintain normal training intensity. I‚Äôve seen athletes literally crash from low-carb diets to the point that they were unable to exercise at all for weeks at a time. Don‚Äôt do that to yourself, respect your body’s needs.

Choose from a wide variety of whole grains such as quinoa, spelt, millet, barley, brown rice and amaranth. We have a tendency in the US to eat most of our carbohydrates as wheat and potatoes, which lead to food sensitivity and blood sugar imbalance respectively. Switch to sprouted breads, crackers made from rice and simple, nutrient dense superfoods like quinoa and barley.


  • Only 5-10% contribution to energy production
  • Greater demand with long duration and depletion of carbohydrate stores
  • Necessary to repair tissue damage that is a normal part of exercise
  • Crucial for blood sugar regulation, body composition and general health
  • General rule: About 1 gram protein per 3 grams carbohydrate

Variety is crucial, be experimental and broaden your palate horizons. Nuts, soynuts and string cheese travel well. Rotate between fish, poultry, meat, beans, some dairy and soy. It is very important to choose organic, hormone-free versions of meats and fish that are wild-caught and as free of heavy metal toxicity as possible. Do not eat fish more than three times per week. Avoid fried foods. Dairy such as milk, yogurt, cottage cheese and Kefir should be organic.


• The potential energy of fat is more than twice that of carbohydrate or protein, but the body doesn’t choose to use it right away
• Fat supplies up to 70% of the energy you need for moderate intensity exercise lasting 4-6 hours
• Be very clear about the distinction between good and bad fats: Saturated fats should be kept under control, but Essential Fatty Acids should be consumed in abundance

Best for cooking are butter (in small amounts), extra virgin olive oil and coconut oil. Only butter should be used when you are heating above medium heat as most oils break down at those temperatures. At all costs avoid trans fats and hydrogenated oils by avoiding processed and fried foods in general.

I recommend daily supplementation of Essential Fatty Acids for most of my patients. You want an oil that contains both EPA and DHA and is monitored for heavy metal toxicity and it should be kept refrigerated after opening.


  • Necessary to maintain adequate blood volume in order to sustain cardiovascular health and overall physical function
  • Regulation of body temperature
  • Compensation for fluids lost as perspiration during exercise
  • Prolonged physical activity, particularly in heat, can lead to a loss of up to 3 litres/hour
  • During exercise, thirst is an unreliable indicator of hydration status, so drink whether you feel like it or not if you exercise for more than an hour
  • Heavy sweaters must drink more than average sweaters
  •  As little as 1-2% decrease in body weight fvrom fluid loss can compensate your athletic ability

To monitor: Measure weight before and after activity, be sure that urine is always clear and frequent

There are many electrolyte and glucose products marketed to athletes. Please be aware that the more glucose a drink contains, the slower it is absorbed from your stomach and into your bloodstream. Use sugary drinks for sugar when you need carbohydrates to maintain your energy or replenish muscle glycogen, but avoid them at all other times and always consume them with plenty of water.

Contrary to popular belief, sodium is the only electrolyte you need to replace with an electrolyte formula. The others are easily replaced within 24 hours of a normal diet, including potassium. Consider salt tablets or low-carb electrolyte replacement products.

If you are exercising an hour or less at a time, water is all you need.