Let’s Talk Marathon Nutrition

So you wanna run a marathon?

With all the hype and excitement around the Boston Marathon on Monday, how could I not join in on the fun?!

You’ve picked your Marathon…  Check!
You’ve found a training plan…    Check!
You’re eating the right foods…    

Proper nutrition is essential!
Eating right will help get you across the finish line.
How many calories do I need in a day?
The three main factors involved in calculating how many calories your body needs per day are:
  • Basal Metabolic Rate (BMR)
  • Physical Activity
  • Thermic Effect of Food

Let’s break it down…


BMR is the amount of energy your body needs to function at rest.  This accounts for about 60 to 70 percent of the calories you burn in one day.

The Harris-Benedict Formula will help you calculate that number!

Adult Males:
66 + (6.3 x body weight in lbs.) + (12.9 x height in inches) – (6.8 x age in years)

Adult Females:
655 + ( 4.3 x body weight in lbs.) + (4.7 x height in inches) – (4.7 x age in years)

Physical Activity

Physical Activity consumes the next highest amount of calories.

Check out the Daily Mile and have them calculate your calories burned for you!

Thermic Effect of Food

Did you know your body uses energy to digest the foods you consume?

Add up the number of calories you consume in a day and multiple this number by 10%.

Note: If you are unsure how many calories you consume in a day, simply add together your BMR plus your physical activity caloric expenditure.

Putting It All Together
BMR + Physical Activity + Thermic Effect of Food 
Total Daily Calories
Nutrient Ratio
Now that you have calculate your total daily calories, it’s time to break that down into the ratio of macronutrients needed for optimum performance:
  • Carbohydrates: 65%
  • Protein: 15%
  • Fats: 20%

Next, let’s find out how many grams of each macronutrient you need.


  • 1 gram of Carbohydrate = 4 calories
  • 1 gram of Protein = 4 calories
  • 1 gram of Fat = 9 calories

For example)

Bobby here is training for a marathon.  He is consuming 3,000 calories a day.

He will need:

  • Carbohydrates: 3,000 x .65 = 1,950 cal / 4g = 488 g
  • Protein: 3,000 x .15 = 450 cal / 4g = 113 g
  • Fats: 3,000 x .20 = 600 cal / 9g = 67 g

Breaking it down into grams makes it easy to find your total by label reading!

How to Fuel

It’s important to get a good balance of fresh fruits, vegetables, grains, healthy fats and protein.

Complex Carbohydrates are Best!
Think oatmeal, whole wheat breads and pasta, potatoes, sweet potatoes, brown rice, high fiber breakfast cereals and beans and lentils.
Go Lean When It Comes to Protein!
Think chicken and turkey breast, tuna, tilapia, 90% lean ground beef, egg whites, beans and low-fat dairy.
Get Your Fats and Oils from Vegetables!
Think olive oil, canola oil, flax seed oil, nuts and avocados.
Foods to Avoid

Limit high fat foods.  Fat takes longer to digest and can leave you feeling sluggish and nauseated.

Coffee and Alcohol in moderation due to their dehydrating effects.

Careful with sugary foods before exercise.  Blood sugar will rise and then drop quickly causing light-headedness and quicker glycogen depletion.

Also, be conscious of portion size.  Eating too much can make for an uncomfortable run.


You are well of your way to a successful marathon completion!

Use online food calculators to look up nutritional information, create weekly meal plans to help you stay on track and focus on your personalized nutrient ratio!

See you at the finish line!

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