What should a runner's macros be?

The International Society for Sports Nutrition (ISSN) recommends the following for a runner’s macros [

1

]:

• 45-55% calories from carbohydrates for general training; >60% for endurance athlete training

• 15-20% calories from protein

• 20-30% calories from fat

Carbohydrates typically make up the largest percentage of calories because they are the body’s preferred source of fuel for moderate- to high-intensity exercise, and are also important for muscle repair and recovery

[1]

. According to the ISSN, individuals running for general fitness can typically meet their carbohydrate needs with a regular diet of 45-55% calories from carbohydrates (3-5 g/kg/day). Athletes pushing performance goals and doing moderate amounts of intense training (2-3 hours/day, 5-6 days/week) can need >60% calories from carbohydrates. 

Protein is also important as it provides the necessary amino acids needed for cell regulation, nerve function, and synthesizing new muscle after a workout

[2]

. Like carbohydrates, protein needs are dependent on the training load. Many runners need more protein than the average person to support muscle building and repair, as well as glycogen repletion after a workout. However, the amount of protein is equally as important as the quality and timing of protein consumption, since this has a big impact on performance, recovery, and training progression.

Fats are an important source of energy, particularly during lower-intensity activities and exercise. While runners don’t seem to have increased fat needs while training like they do with protein and carbohydrates, choosing high-quality fats can support hormonal health and reduce inflammation, both of which are important when it comes to high-intensity and endurance exercise

[3]

.