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Aug 31, 2021 | Reverberating Science

Nutrition and Supplement for Endurance Part 1, Macronutrients

Reproduced by Rodrigo Fava Neto

This article is a comprehensive review in a consolidated form and offer practical, evidence-based recommendations that are valuable and directly applicable to endurance athletes.  Published in 2019 in the National Library of Medicine (USA). Let’s start with Macronutrients as Part 1, and Hydration and Supplements will come next.

Participation in endurance events has increased, with 3.5 million triathlon participants worldwide in 2015. In recent years, there has been a shift in running from standard marathon races to “other distance” races. Furthermore, ultra-endurance events are also gaining popularity. Ultra-endurance activities are typically defined as events lasting at least 4 to 6 h duration. Prior studies have illustrated the challenges that ultra-endurance exercise exerts on the body in terms of fatigue, sub-optimal nutrition, and energy deficit, and brings awareness to the potential medical complications of ultra-endurance exercise underscoring the importance of an individualized nutritional approach.

If you like the excerpts I transcribed here, I recommend reading them in full, link at the end of the text.

approx. 5 minutes reading

In percentage of calories consumed diary, according to the USA National Academy of Science.


1g = 4 kcal

  • Min 45% 45%
  • Max 65% 65%


1 g = 4 kcal

  • Min 10% 10%
  • Max 35% 35%


1g = 9 kcal

  • Min 20% 20%
  • Max 35% 35%

Carbohydrate (CHO)


5 to 12 g / kg / day

Carbohydrate, as blood glucose and muscle glycogen, has the advantage of generating more ATP (“energy”) per volume of oxygen, compared to fat, however liver and muscle carbs stores is limited.

The Academy of Nutrition and Dietetics (AND), Dietitians of Canada (DC), and the American College of Sports Medicine (ACSM) recommends that:

  • moderate exercise, 1 h / day, requires 5 to 7 g per kilogram of bodyweight per day, g / kg / day.
  • moderate to high intensity exercise, 1 to 3 h / day, mandates 6 to 10 g / kg / day.
  • Ultra-endurance athletes with extreme levels of commitment to daily activity, 4 to 5 h of moderate to high intensity exercise every day, may need up to 8 to 12 g / kg / day.

The International Society of Sports Nutrition (ISSN) recommends in order to maximize glycogen stores athletes should employ an 8 to 12 g / kg / day high Carb diet.



1.2 to 2 g / kg / day

Athletes require higher protein intakes than the current Recommended Daily Allowance (RDA) of 0.8 g / kg / day in order to achieve training adaptations  and improve performance.

The AND, DC, and ACSM all recommend protein ingestion for athletes in the range of 1.2 to 2.0 g / kg / day, with the ISSN recommending 1.4 to 2.0 g / kg / day.

  • Strength and power athletes are typically recommended to consume in the higher range, 2 g / kg / day.
  • Endurance athletes, the lower range, based on individual needs, 1.4 g / kg / day.

Muscle protein synthesis can only be stimulated with doses at least 3 to 5 h apart. Therefore, the AND, DC, and ACSM recommend spreading protein dosing at approximately 0.3 g / kg every 3 to 5 h throughout the day.



more than 20%

In comparison to carbohydrate, proper fat intake gathers less consideration by endurance athletes but is a worthy fuel source.  Oxidation of glycogen provides only  approximately 2,500 kilocalories of energy before depletion, whereas oxidation of fat provides at least 70,000 to 75,000 kilocalories of energy, even in a lean adult.

Fats are fundamental components of cell membranes, playing roles in signaling and transport, nerve function, providing insulation and vital organ protection, and are the source of essential dietary fatty acids and must account for above 20% of total energy. Athletes who chronically restrict fat to less than 20% of total energy are at risk of low intake of fat-soluble vitamins and carotenoids, essential fatty acids including n-3 (omega-3) fatty acids, and possibly conjugated linoleic acids (CLA).


“Loading” – Prior to the race, if the event is to last less than 90 min, a simple “topping-off” of glycogen stores to replenish muscle and liver glycogen lost during the prior day has been recommended typically with a Carbs rich diet of at least 6 g / kg and up to 7 to 12 g / kg in the 24 h period before the event. 

For events lasting more than 90 min however, glycogen supercompensation, or “carbo loading,” in the preceding 36 to 48 h may help improve performance by 2 to 3%. 

In the final 1 to 4 h prior to the event, a single dose of 1 to 4 g / kg Carbs is recommended for a final top-off of liver glycogen stores, as typically endurance events occur in the early morning directly after the overnight fast which depletes liver glycogen. 

“Fueling” – For events lasting less than 60 min, no Carbs ingestion is required. However, for activities more than 60 min, active fueling strategies are recommended to maintain Carbs accessibility. For events lasting 1 to 2.5 h, 30 to 60 g / h is commonly recommended in a 6 to 8% Carb solution, concentrations typically found in commercial sports drinks, ideally consumed every 10 to 15 min to maximally spare glycogen stores. For events lasting  above 2.5 h, higher Carbs intakes of 60 to 70 g / h, and up to 90 g / h are associated with improved performance. Research demonstrates that Carbs oxidation peaks at a Carbs ingestion rate of 1.0 to 1.1 g / min.


Compared to resistance exercise, few studies have been done on pre- and during exercise protein intake with endurance activities, but available evidence shows it may improve same day and next day endurance performance.

Exhaustive endurance exercise and significant eccentric activities e.g., marathons, downhill running, and obstacle course races can result in catabolism of muscle, especially in the setting of inadequate protein or reduced energy availability and does raise muscle creatine kinase levels, a marker of muscle damage.  If tolerable, the athlete may therefore consider a pre-exercise dose of 0.3 g / kg protein according to gastrointestinal  tolerance.

During endurance exercise, if particularly intense or significant eccentric exercise, approximately 0.25 g / kg protein per hour when taken along with carbohydrate is recommended by the ISSN to minimize potential muscle damage.

Timing and dose are also shown to be important; 0.25 to 0.3 g / kg of a quality protein source in the immediate 0 to 2 h post exercise provides approximately 10 g of essential amino acids (EAA), which maximally stimulate Muscle Protein Synthesis and the associated signaling proteins mTOR, p70s6k, Akt needed for protein synthesis.


Some ultra-endurance athletes have recently become interested in ketoadaptation (becoming “fat-adapted,” or “training low”) with a high fat, low carbohydrate diet. This renewed interest is based on the higher oxidation of fat vs. glucose in lower intensity, less than 70% VO2max, exercise states typically seen in ultra-endurance events. 

Some athletes then decide to carbo load just prior to the event, so that they can in essence “train low, race high”: maximize both fat oxidation pathways at lower intensities, less than 70% VO2max, and glucose oxidation pathways at higher intensities, more than 70% VO2max. However, if the athlete’s focus is on racing and improving performance times, a high fat, low carbohydrate diet restricts that athlete’s ability to train and race at higher intensities.

Endurance athletes are encouraged to follow public health guidelines to ensure adequate fat intake, and only consider limiting fat intake pre-race during a Carbs loading phase or pre-race if there are gastrointestinal  comfort concerns.


To illustrate Macronutrient Recommendations

* Considering an endurance athlete weighing 80kg (176 pounds) who practices 1 hour of moderate activity a day, burning 3200 kcal per day. It is important to emphasize that this is a possible scenario among the multiple possibilities within the range proposed by the article.

On Training Day *

  • 480g (16.9oz) of Carbs, at 6 g / kg / day, or 1920 kcal 60% 60%
  • 120 g (4.23 oz) of Protein, at 1.5 g / kg / day, or 480 kcal 15% 15%
  • 89 g (3.14 oz) of Fat, or 800 kcal 25% 25%

On Day Before 90 min Race *

  • 640 g (22.6 oz) Carbs Loading at 8 g / kg / day, or 2560 kcal 80% 80%
  • 80 g (2.82 oz) of Protein, or 320 kcal 10% 10%
  • 36g (1.27 oz) of Fat, or 320 kcal 10% 10%

On Race Day, Pre Race *

1 to 4h prior to event, at 2 g / kg

immediately prior, equivalent to 0.3g/kg

Do not restrict below 20%

On Race Day, During 90 min Race *

if race last less than 2.5 h

if high intensity

Do not restrict below 20%

On Race Day, After Race *

first 24h, at 8 g/kg/day

equivalent to 0.3g/kg, immediately after

Do not restrict below 20%

link to the article.


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