How much protein do runners need?

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As runners, it’s not easy to find a definitive answer on how much protein is actually needed to optimise performance and recovery. This article clears up the ambiguity around protein requirements for runners and uses the latest sport-science research to provide precise recommendations.

Article Summary

• 1.65 grams of protein per kg of body mass per day is the minimum intake required for runners to support full recovery, based on the conclusive findings of three recent high-quality studies. However, this amount only reflects the average requirement—meaning it may be insufficient for up to half of all runners.
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• 1.8 grams of protein per kg of body mass per day is appropriate for the vast majority of runners and is supported by the consistent findings of multiple recent studies. This article concludes that runners should aim to achieve this protein intake.
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• During periods of very intense or high volume training, or when in a caloric deficit, protein intake may need to increase towards 2 g/kg/day, to support full recovery.

Navigation

• Free Macro Calculator for Runners
• Why Runners Need Protein
• Optimal Protein Amount for Running
• How Optimal Protein was Established
• When to Increase Protein Intake
• Myths Surrounding Protein and Running
• Supplementation

Free Macronutrient Calculator for Runners

Use our free online macronutrient calculator for runners to easily determine your daily protein, carbohydrate, and fat requirements as a runner. It simplifies the process of establishing your ideal macronutrient targets.

Why Runners Need Protein

Proteins are essential for the body. They comprise the major structural elements of all cells, catalyse virtually all chemical reactions in the body, form the primary components of muscle and connective tissue, and regulate the immune system (Wu, 2016). However, when considering running specifically, the primary roles of proteins are to facilitate the repair, remodelling, and recovery of muscles and soft tissues.

Protein’s role in facilitating muscle growth is clear, and I have written about this in a previous blog. However, for the endurance athlete, building muscle is not the goal as excess muscle mass is largely considered detrimental to performance. However, the idea that consuming more protein makes a runner bigger, is a myth, as discussed later in the article.

For runners, protein plays a key role in accelerating muscle recovery, facilitating training adaptations, and ultimately increasing the total volume of training that can be performed and recovered from. Muscle tissue is composed of protein, and running places stress on these tissues, causing microdamage that must be repaired for adaptation to occur. Optimizing recovery through adequate protein intake is essential, as recovery determines how much high-quality training can be sustained without the negative consequences of under-recovery, such as injury, chronic fatigue, or performance decline.

Bottom line: the better the recovery, the more training and mileage can be completed, and the better the runner becomes. Consuming enough protein plays a critical role in this process. 

Optimal Protein Amount for Running

There have been three primary studies (1, 2, 3) assessing the optimal protein requirements for endurance athletes. The first examined triathletes, while the second two specifically looked at runners. Studies two and three took a very similar approach: endurance-trained runners completed three consecutive days of training totalling 35 km (10 km on day 1, 5 km on day 2, 20 km on day 3). On the third day, total protein requirements were assessed, and all three studies concluded with nearly identical findings regarding the minimum protein needed for optimal post-training repair processes. This figure was 1.61-1.65 grams of protein per kilogram of body mass per day. It is unusual in scientific literature for multiple studies to conclude such similar values; therefore, the evidence supporting this protein requirement is strong.

How the Optimal Protein Requirement was Established

I'm including the studies' methods here simply because it is interesting to understand how the researchers established the protein requirement values.

Study 1 used the nitrogen balance method. Protein contains nitrogen, which is mostly excreted in urine. By comparing nitrogen in (from protein intake) to nitrogen out (via urine, sweat, and feces), researchers can tell if the body has enough protein.

• Positive balance: more nitrogen in than out → indicates extra protein available for growth, repair, or recovery.
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• Negative balance: more nitrogen out than in → suggests muscle breakdown or inadequate protein intake.
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• Balanced: nitrogen in equals nitrogen out → protein needs are being met for maintenance and recovery.

Once needs are met, extra protein offers little added benefit, and the excess nitrogen is simply excreted. 

Studies 2 and 3 (the running specific studies) used an even more precise method called Indicator Amino Acid Oxidation (IAAO). In this technique, researchers traced the metabolism of a labelled amino acid ([¹³C]phenylalanine) by measuring carbon dioxide in exhaled breath. Greater exhalation of ¹³CO₂ indicated that the amino acid was being oxidized for energy rather than used for muscle repair. This allowed the researchers to determine the threshold at which dietary protein is no longer preferentially used for recovery. IAAO is considered a gold standard for assessing protein requirements, and the finding of 1.61-1.65 g/kg/day across multiple studies provides very strong support for this value in endurance-trained runners, however, it may still vary with individual needs and training load.

Something worth noting, however, is that these values represent the average requirement—sufficient for approximately 50% of the population. Kato et al. (2016) and Williamson et al. (2023) concluded that higher intakes of 1.85–2.02 g/kg/day (or 0.84–0.92 g/lb/day) would be optimal for nearly all individuals. The most recent research on this topic came in 2025 in the form of a literature review comparing numerous endurance training studies and concluded a recommendation of 1.8 g/kg/day of protein. It is also my opinion that this value represents the most appropriate target that will be sufficient for the vast majority of runners. 

Summary

• 1.65 g/kg/day is a sufficient lower-end target for daily protein intake. However, this amount only reflects the average requirement—meaning it may be insufficient for up to half of all runners.
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• It is recommended to consume 1.8 g/kg/day, which aligns with the most recent 2025 literature review on protein requirements for endurance athletes.

A note on heavy training volume

The three studies referenced did not involve particularly high training volumes. Heavier training places greater stress on the body’s musculature and increases recovery demands. Therefore, protein requirements may exceed the values recommended by these studies when training is especially intense or taxing. This further supports why a ‘safer’ intake to meet training needs is 1.8 g/kg/day.

When to Increase Protein Intake Further

• During heavy training: As mentioned above, heavier training burns more energy and places greater stress on the body. Following high-volume days, I recommend protein intake be at least 1.8 g/kg/day, or even slightly higher, towards 2 g/kg/day.
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• When in a caloric deficit: Another time to increase protein intake is during a caloric deficit—when you're burning more calories than you're consuming. This can occur during weight loss or periods of high training volume without a matching increase in food intake. In a calorie deficit, the body burns dietary protein for energy due to reduced energy availability (5). To help offset this and still recover optimally, again, aim for a higher protein intake, towards 2 g/kg/day.

Myths Surrounding Protein and Running

Myth: Greater protein = greater muscle mass, so runners shouldn’t eat protein

This is not the case. Increasing protein intake alone does not lead to significant muscle gain. To gain significant muscle mass, consistent resistance training is needed alongside a caloric surplus (4).

Protein + Resistance Training + Caloric Surplus = Muscle Mass Gain

Protein + Running ≠ Muscle Mass Gain

Note: If you're new to running or returning after a break, you may gain some muscle mass while also losing fat mass. However, this is essential adaptation and the principle remains—total body mass will not increase unless energy intake exceeds expenditure.

Why running + greater protein intake does not increase muscle mass

Endurance running primarily recruits type I muscle fibres; these are fibres responsible for producing energy aerobically using oxygen. Running promotes adaptations that improve their efficiency and fatigue resistance, which leads to better running. However, type I fibres have limited hypertrophic (growth) potential and do not significantly increase in size. In contrast, type II fibres—especially type IIX—are more responsive to growth stimuli and are predominantly activated during resistance training, sprinting, or jumping. Type I fibres are smaller in cross-sectional area and have lower hypertrophic potential compared to type II fibres. As running volume increases, there is a greater reliance on type I fibres and reduced activation of type II fibres. Over time, this shift in recruitment and adaptation can lead to a reduction in muscle mass, especially in the absence of strength training. This sport-specific muscle adaption contributes to why elite long-distance runners typically carry minimal muscle mass. It also dispels the myth that greater protein will increase muscle mass alongside running, as running simply does not provide a stimulus for muscle growth (6). 

Furthermore, there’s a common misconception that running makes you strong. In reality, running improves endurance and aerobic efficiency, not muscular strength. It enhances your ability to sustain effort over time, but true strength gains come from resistance training and therefore, it's highly recommended all runners undergo some resistance training alongside running to preserve strength, decrease injury risk, and improve running economy. 

Supplementation

Consuming optimal protein levels through diet alone can be challenging, which is why protein powders exist. At Thrive, we offer both plant-based protein and whey protein isolate, both scientifically designed to provide all the essential amino acids needed for recovery. Our proteins are made with the cleanest ingredients, taste amazing, are third-party tested, and proudly made in Canada.

About the Author:

Joe is a certified personal trainer, strength and conditioning coach, and nutrition coach. He holds a Bachelor of Science with Honours in Sport and Exercise Science, graduating with First Class standing. During his studies, Joe focused on human physiology and performance, and he applies this knowledge of exercise science to his work with Thrive. He is the co-founder of Thrive Protein, a Canadian family-run supplement company focused on clean, scientifically backed nutrition products — including protein powders, greens, and electrolytes.

References:

PROTEIN STUDIES

Houltham, S. D., & Rowlands, D. S. (2014). A snapshot of nitrogen balance in endurance-trained women. Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme,39(2), 219–225. Link

Kato, H., Suzuki, K., Bannai, M., & Moore, D. R. (2016). Protein Requirements Are Elevated in Endurance Athletes after Exercise as Determined by the Indicator Amino Acid Oxidation Method.PloS one,11(6), e0157406. Link

Williamson, E., Fung, H. J. W., Adams, C., West, D. W. D., & Moore, D. R. (2023). Protein Requirements Are Increased in Endurance-Trained Athletes but Similar between Females and Males during Postexercise Recovery.Medicine and science in sports and exercise,55(10), 1866–1875. Link

SUPPORTING REFERENCES

Jeukendrup, Asker. (2003). High-carbohydrate versus high-fat diets in endurance sports. Schweizerische Zeitschrift fur Sportmedizin und Sporttraumatologie. 51. Link

Wilson, J. M., Loenneke, J. P., Jo, E., Wilson, G. J., Zourdos, M. C., & Kim, J. S. (2012). The effects of endurance, strength, and power training on muscle fiber type shifting. Journal of strength and conditioning research, 26(6), 1724–1729. Link

McArdle, W. D., Katch, F. I., & Katch, V. L. (2015). Exercise physiology : nutrition, energy, and human performance(8th ed). Wolters Kluwer Health/Lippincott Williams & Wilkins.

Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance.Journal of the Academy of Nutrition and Dietetics,116(3), 501–528. Link