Fill that tank with carbs

Think of the human body much like a car; to get from A to B you need to put the correct fuel in. If your journey is a long one or you decide to put your foot down, a stop to the garage for a fuel refill will be required. This is no different for a triathlete. The more you do, the more you need. Let Platform Nutrition guide you the does and don’ts of eating right for a triathlon.   

Fill up your fuel tank

Just like a car, the human body has a fuel tank in which it can store carbohydrate; however the capacity is only so big. This is extremely noticeable on the longer race distances where individuals start to run out of carbohydrate (glycogen depletion) and fatigue sets in. To keep going, refuelling on the go will be required. As a guide, a full store of carbohydrate equates to approximately 90 minutes to 2 hours of continuous exercise. A great example of this is the ‘hitting the wall’, that many runners experience at about mile 18-23 of a marathon but this can be avoided with the correct nutritional strategy. 

How much fuel do I need?

A triathlete’s carbohydrate requirement will depend on a number of physiological affects including: exercise intensity and duration, environmental conditions, total energy needs (across the day or for a specific session), exercising goal and the desired adaptive response.

Carbohydrate needs for endurance performance

Exercise Load


Carbohydrate amount

Moderate exercise

~1 hour a day (h/d)

5-7 g/kg of body weight/day

Heavy exercise

1-3 h/d mod/high intensity

6-10 g/kg/d

Very High exercise

>4-5 h/d mod/high intensity

8-12 g/kg/d

(adapted from the ACSM, Nutrition & Athletic Performance, 2016)



Fuelling Strategies



Carb Loading

Event preparation lasting > 90 min

36-48 h of 10-12 g/kg/d

Speedy Refuelling

<8 h until next session or event

1-1.2 g/kg/h for the first 4 hours and then normal feeding

Pre Event

1-4 hours before event

1-4 g/kg

During exercise

<45 min



45-75 min

Small amounts


1-2.5 h

30-60 g/h


>2.5-3 h

Up to 90 g/h


Carbohydrate food sources

For a nutrition plan to be successful it should be tailored to the individual - tried, tested and refined. The carbohydrate intake guidelines are a starting point but will need to be adapted to suit a triathlete’s needs. It’s quite likely that a triathlete’s carbohydrate need, will not only alter in line with the training programme but will differ on a day-by-day basis depending on the demand. But what type of carbohydrate should be consumed? There is good scientific evidence to suggest that neither the glycaemic load nor the glycaemic index of carbohydrate meals affects the metabolic or performance outcomes. On the contrary, high glycaemic carbohydrate such as isotonic sports drinks, gels and bars, provide appropriate and convenient food alternatives to consume during exercise.

Carbohydrate is an important macronutrient that should be tailored to your exercising goal. The requirements of such, should be balanced with respect to the exercising need and most importantly to the individual. Carbohydrate is only part of story, but failing to plan your needs could result in a reduction or depletion of your carbohydrate stores and therefore, like your car, a premature end to the journey.