Nutrition is often an overlooked element of marathon training. The right nutrition plan will make those long workouts seem so much easier!

Food is your source of energy. All food is made up of carbohydrates, protein, fat, and fiber. Carbohydrates are linked to energy production, complete proteins are linked to tissue repair and building, fat provides fuel for the body, and fiber is fiber.

Most foods will have traces of all of these macronutrients, but each is typically rich in one. ALL are necessary in your diet.


Your body burns carbohydrates more efficiently than fat or protein. Consider increasing your carbohydrate intake to 60-70% of your daily food intake.

Runners benefit the most from the amount of carbohydrates stored in the body. Carbohydrates produce more energy per unit of oxygen consumed than fats. What this means is that you get more energy for running when your body burns carbohydrates than when your body burns fat or protein. Because oxygen is often the limiting factor in long duration events, your body will find it easier to use the energy source that requires the least amount of oxygen per kilocalorie of energy produced. (energy is measured in kilocalories)

Your body produces energy by converting carbohydrates into glucose. When you exercise at a moderate pace, carbohydrates provide 40 to 50 percent of your energy requirement. As you begin to run stronger, carbohydrates provide a greater percentage of your energy needs. It is difficult for your body to break down protein and fat into glucose to provide energy. Therefore, your body burns carbohydrates first. The harder you work, the more difficult it becomes for your body to devote energy to breaking down protein and fat. That energy could be used to propel you forward in the race.

The best sources of carbohydrates for your marathon training

Carbohydrate needs are commonly based on the runner’s body size and activity level. Runners performing low intensity, moderate duration exercises require 5 to 7 g of carbohydrates per kilogram of body weight. In contrast, those who participate in long-duration, high-intensity exercise require 7 to 12 g of carbohydrates per kilogram of body weight.

Not all carbohydrates are the same.

The best sources of carbohydrates in your diet

  • Fruit,
  • vegetables,
  • Integral rice,
  • enriched whole grain breads,
  • whole grain cereals,
  • oatmeal,
  • Beans,
  • vegetables and
  • sweet potatoes

(Note: Cheetos, cookies, and chips are not on the list.)


The next macronutrient the body should use during exercise is fat.

Fat is not the enemy. The fat created from too much cheetos is. (Remember that excess of any macronutrient (carbohydrates, proteins, fats) turns into fat). For moderate exercise, about half of the total energy expenditure is derived from free fatty acid metabolism. If the event lasts more than an hour, the body can use mainly fat for energy. The use of fat for fuel depends on the duration of the event and the condition of the runner. Trained athletes use fat for energy faster than untrained athletes. (This is one of the long-run adaptation mechanisms in marathon training.)

The best sources of fat in your diet

  • Walnuts
  • Seeds
  • Nut butter
  • Fatty fish
  • Fish oil supplements
  • Linseed oil
  • Safflower oil
  • Canola oil
  • Sunflower oil
  • Corn oil
  • Avocados
  • Egg yolks


After carbohydrates and fats, proteins provide the body with energy. You also need protein to repair muscle tissue that is damaged during exercise. While exercise can increase an athlete’s need for protein, most Americans tend to eat more than the recommended amounts of protein.

A protein intake of 10 to 12 percent of total calories is sufficient. Most authorities recommend that endurance athletes consume 1.2 to 1.4 grams of protein per kg of body weight per day. Remember, the extra protein is stored as fat.

It is doubtful that you need additional protein, which is likely that you need to be more aware of where you are getting your protein.

Women trying to lose weight by cutting calories often forgo healthy protein sources for bagels. Don’t get me started on my “bagels are empty calories” spiel; For now, all I’ll say is that high-protein foods include lean pork and beef, poultry, fish, eggs, beans, tofu, and low-fat dairy. Include lean sources of protein in your marathon training diet.

The best sources of protein in your diet

  • Lean pork and beef
  • Poultry
  • Fish
  • Eggs
  • Low-fat dairy products.
  • Broccoli
  • Beans
  • Corn


Fiber helps the body stay healthy and can prevent heart disease. Getting enough may be easier than you think.

Soluble fiber, found in oats, barley, beans, apples, oranges, and other fruits and vegetables, can help prevent heart disease by lowering LDL or “bad” cholesterol levels. Set a goal of eating 20 to 35 grams of fiber every day. The best way to do this is to eat a wide variety of whole grains, nuts, seeds, beans, fruits, and vegetables.

Fiber also keeps the intestines regular. This is key to avoiding discomfort in your long training runs.

The best sources of fiber in your diet

Include more fiber in your meal plan by adding vegetables to casseroles and casseroles. Add oatmeal to meatloaf, breads, and cookies. Fruit on cereal, as a snack and in salads are other options.

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