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Nutrition for Beginner Triathletes: Macros 101

Nutrition for Beginner Triathletes: Macros 101 Run Tri Bike Magazine Stevie Lyn Smith RD

In endurance sports you’ll often hear athletes talk about different approaches to nutrition and fueling. You may have heard things like ‘training low’ or ‘high-fat, low-carb’ or ‘fasted workouts’. While nutrition is not ‘one-size-fits-all’, a number of the approaches to endurance sports nutrition can be strongly influenced by fads or our current diet culture. Here, we’ll help you to understand the basics on macro and micronutrients and what you need to know as an endurance athlete.

Nutrition for Beginner Triathletes: Macros 101

What are macronutrients?

Macronutrients are nutrients that the body requires in large amounts as macros provide the body the majority of the calories it needs. These macros are carbohydrates, fat, and protein. It is important to note that while alcohol does provide calories, and is made up of the aforementioned macronutrients, it is not necessary for your body to function and can sometimes hinder athletic performance.

There are a number of factors to consider when determining how much of each macronutrient you need. This will vary not just between individuals, but also as training volume, intensity, and goals change.


As the main source of fuel used in moderate to high intensity endurance activities, consider this macro your best friend as an endurance athlete. Our bodies can store carbohydrates– up to 400-500 grams in both the muscle and the liver. That equals about 2,000 calories worth of fuel! Consuming enough carbohydrates before and after your workouts will help keep these stores from being depleted and promote adequate recovery post-workout.

When we exercise, our body will take this stored carbohydrate known as glycogen, and convert it to glucose for the body to use. As the intensity of your workout goes up, your body will burn through these stores more quickly. While that may seem like an extraordinary amount of fuel, these stores aren’t limitless. If you plan to workout for over an hour, you should be fueling with carbohydrates during your workout.

Despite knowing how consuming enough carbohydrates can improve performance and recovery, athletes still fail to get enough in their diet(1). How many carbohydrates you need to eat will vary between individuals but here are some starting guidelines for moderate to high volume athletes (pssst- if you are training for any distance race, this is you!):

5-8g/kg/day for moderate levels of training
8-10g/kg/day for high intensity training days(2)

Here are some quick tips on how to incorporate carbohydrates:

Aim to get most of your carbohydrates from a variety of fruits, vegetables, legumes, and a variety of whole grains. This will also help provide a range of micronutrients.
Consume carbohydrates before and after your workouts. This will help your performance, recovery, and help to meet your overall energy needs (3).
When exercising for over 2 hours you should consume carbohydrates during your workout to improve performance and prevent fatigue. These should be coming from easily digested sources. A few examples include sports drinks, gels, and chews(4).


Eating enough protein is important to support muscle repair and recovery along with preventing injury and muscle breakdown. It is also critical for other body functions including the production of hormones, enzymes, and neurotransmitters. In addition, research has shown that runners, cyclists, and triathletes are susceptible to falling short on their protein needs. (4)

How much protein you need to eat will also vary based on a number of factors including your age, sex, weight, activity levels and fitness goals. While eating enough is important, it’s not that simple. You should also be paying attention to the quality of your protein sources. Different types of protein will be broken down and absorbed at different rates. Some examples of high quality protein include fish, chicken, egg whites and lean cuts of beef.

Here are some quick tips to meet your protein needs:

Protein powders can be a great tool to meet protein needs, but shouldn’t be relied on
For athletes training at moderate levels 1.2-2.0 g/kg/day is the goal and 1.7-2.0 g/kg/day for high intensity athletes (4,5)
Consider spacing out your protein every 3-4 hours in about 20 gram portions. This has been shown to have the greatest effect on muscle repair and growth (kersick). Of course, this may vary between each individual.


At nine calories per gram, this macronutrient not only helps an athlete meet their energy needs, it is the preferred fuel source for your muscles during lower intensity workouts. It also helps absorb fat-soluble vitamins (A,D,E, and K), provides protection for your organs, and promotes hormone health.

How much of this macro you need won’t change based on your training volume or intensity, but it is still important to make sure you are eating enough. Aim for 25-30% of your total calories, which is easily done if you are eating a balanced diet. Opt for mostly unsaturated fats from foods like avocados, walnuts, flax, and fatty fish just to name a few. Saturated fats like those found in fried and processed foods, high fat cuts of meat, palm and coconut oils can negatively impact blood lipid, or cholesterol levels.

How do you know if you’re nailing your nutrition?

You should FEEL good! If you can perform in most of your workouts (we all have bad training sessions!), have energy to get through your days, and aren’t frequently getting sick or injured, these are all good indicators that you’re meeting your body’s needs. If you are still unsure if you’re meeting your nutrition needs or want more individualized help, reach out to a registered sports dietitian.



  1. Burke, L.M., Cox, G.R., Cummings, N.K. et al. Guidelines for Daily Carbohydrate Intake. Sports Med 31, 267–299 (2001).
  2. Burke L, Hawley J, Wong S, Jeukendrup A. Carbohydrates for training and competition. J Sports Sci. 2011;29(sup1):S17-S27. doi:10.1080/02640414.2011.585473
  3. Burke L. Energy Needs of Athletes. Canadian Journal of Applied Physiology. 2001;26(S1):S202-S219. doi:10.1139/h2001-055
  4. Cermak N, van Loon L. The Use of Carbohydrates During Exercise as an Ergogenic Aid. Sports Medicine. 2013;43(11):1139-1155. doi:10.1007/s40279-013-0079-0
  5. Kerksick C, Wilborn C, Roberts M et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr. 2018;15(1). doi:10.1186/s12970-018-0242-y
  6. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2017;52(6):376-384.


Stevie Lyn Smith RD Run Tri Bike Magazine Contributor

Stevie Smith is a Registered Dietitian, board certified in sports nutrition, who is here to help you fuel your busy lifestyle. As a life-long athlete, she is passionate about helping active individuals to improve performance without sacrificing their health and happiness.