The Tri-Athletes’ Nutritional Triple Threat – Carbohydrate!

The Carbohydrate triple threat when preparing for a triathlon:

1.)  Carbohydrate before the event

2.)  Carbohydrate during the event

3.)  Carbohydrate after the event

OK the theory may not be rocket science, and this is by no means an exhaustive list of all things to consider when preparing for a triathlon, but carbs are definitely some of the most important nutrients to monitor…and get right! Aside from nutrition, training is hugely important (this is a given), but adequate training splits for a triathlon cannot occur without the right fuel. Nutritional preparation should occur on a periodised plan, meaning nutritional macrocycles should start months in advance. So to explain, getting the foundations right involves consuming a base of starchy carbohydrate, lean animal protein and/or non-haem protein (plant based), as well as fruit and veg, dairy, a fat source, and the right balance of sport supplements too. To explain all of these nutritional components in depth is sadly beyond the scope of this article, so today we focus on arguably the most important endurance nutrient…carbohydrate. Specific dietary manipulations will take place nearer to the event, but in the early stages it’s about getting the foundations right.

Macronutrients (Macro’s)

As mentioned above, protein, carbs and fat control is paramount, and a good place to start is the macro ratio of 50: 30: 20 i.e. 50% carbs, 30% fat and 20% protein. This differs from the average bodybuilder/fitness model who will generally have lower carbs relative to protein e.g. 40: 30: 30 carbs, fat and protein respectively. Once an athlete has these basics in place, attention should be paid to the timing of specific nutrients. It is important that you get the macro balance correct right the way up to competition time, but there are specific timing considerations to bear in mind the night before exercise, the morning before, directly before, directly after, and before bed.

Carbs before training

This starts the night before in the form of meal, fluid and supplement preparation for the next day, as well as the physical consumption of nutrients ready to fuel you overnight and the next morning such as carbs for glycogen replenishment, protein for muscle repair and recovery, as well as staving off muscle catabolism whilst sleeping, and fat for anti-inflammation and maintenance of joint integrity. Make sure you fully stock your glycogen stores by consuming starchy carbs approx 2-3 hours before bed, follow this up with a starch first thing in the morning such as porridge oats with some blood sugar regulating cinnamon and joint lubricating coconut oil. The rest of the day is going to be carb loading ready for the event, so your food prep the night before should have included wholegrain or basmati rice, pasta, potato or sweet potato and carb based snacks such as rice cakes to ensure your carb levels are as high as possible (Metzger, 2008).

Starchy carbs are the main fuel for any activity above and beyond 65% of maximum exertion, emphasising the importance of getting it right. Every top athlete in the world maximises carbohydrate when they train and perform, you just have to take the endurance phenomenons of the Tour de France last month, the fast twitch powerhouses of the 100m sprint last week, or the endurance and power hybrids that are triathletes.

Glycogen Supercompensation aka ‘Carb loading’

Carb loading is all about maximising your glycogen stores (stored carbs), our bodies preferred energy source. Our bodies store on average 600g (400-600g) of glycogen within our muscles, with around 100-120g stored in our liver. During a carb loading phase you should aim to reduce the amount of carbs you consume approx 2 weeks prior to the event, effectively ‘training low’ or low carbs, then approx 1 week before the event the athlete should begin to carb load whilst reducing the intensity and volume of exercise i.e. consume a high volume of carbs such as 400-600g per day, or around 5-7g carbs per kg body weight. It is not unusual for the carb intake to reach 70-90% carbs during the carb loading phase!

Example Diet Plan

Below is a typical Carb – loading diet providing 3300kcal and 560g Carbohydrate equating to 70% Carbs and 7g Carbs per kg bodyweight for an average 75kg person:


45g porridge oats with 350ml skimmed milk (250kcal; 16.5g Protein; 42g Carbs)
low fat yoghurt + 1x Banana and blend (460kcal; 56g Protein; 38g Carbs)
200ml Fresh orange juice (100kcal; 1g Protein; 20g Carbs)

Mid- Morning

1x Apple (46kcal; 11g Carbs)
2x Tangerines (50kcal; 10g Carbs)
350ml can soft drink (150kcal; 35g Carbs)


350g baked sweet potato (250kcal; 4g Protein; 69g Carbs)
30g low fat cheese (117kcal; 7g Protein; <1g Carbs)
200g baked beans (164kcal; 10g Protein; 27g Carbs)

Mid- Afternoon

High 5 Sports Bar (203kcal; 3g Protein; 37g Carbs)
500ml isotonic drink (70kcal; 17g carbs)


80g cooked wholemeal pasta (250kcal; 10g Protein; 59g Carbs)
160g boiled chicken breast in 300ml (146kcal; 32g Protein)
200g tinned chopped tomatoes (44kcal; 1g Protein; 7g Carbs)
&frac12; clove garlic
Mixed herbs

500ml isotonic drink (70kcal; 17g carbs)


Banana smoothie made with 200ml semi-skimmed milk, 1x banana and 15-20g honey (200kcal; 8g Protein; 47g Carbs)
2x slices wholegrain bread and 50g Jam (210kcal; 50g Carbs)


The ‘Carb Triple Threat’

Carbs immediately before exercise

It is integral that you get this right. For optimal results consume around 700ml of an isotonic or carb based energy drink within an hour before exercise, and a great example includes High 5 Energy Source 2:1, High 5 Isotonic or Science in Sport GO Energy.

Carbs during Exercise

We have all hit that ‘wall’ when running, cycling or performing endurance sports due to the depletion of our bodies preferred energy source, glycogen (stored carbs). In order to stave the ‘low’ off or smash the wall down once the ‘low’ sets in, try consuming an isotonic beverage at intermittent stages during the event, these can be strategically placed at refuelling points during endurance events. Should one feel that the volume of fluid they have to consume is too much to meet demand resulting in bloating, nausea and GI upset then energy gels are a great option. Examples of energy gels include High 5 Iso Gel and Science in Sport GO Isotonic Energy Gel. At most our bodies can absorb/tolerate 90-100g of carbs per hour, so getting these is when possible is of paramount importance.

Carbs after exercise

Repletion and recovery time! Ingestion of a readily absorbed source of carbs directly after exercise (such as 500-700ml of an isotonic drink) is optimal for maximising recovery and repletion ready for the next day’s training. Our bodies can oxidise (use) carbs at a rate of around 1g per minute, but if we combine glucose and fructose, the oxidation rate increases! Therefore it is the carb type as well as timing that matters, this is because different carbs use different absorptive sites, for example glucose is absorbed via the GLUT-1-4 transporters, whilst fructose is absorbed via the GLUT – 5. Consequently total carb absorption is greater when a source of both glucose and fructose is consumed, meaning there is a greater carb oxidation rate, less risk of nausea and vomiting, and greater energy levels. Optimal glucose to fructose ratios are 2:1 respectively i.e. 2 glucose to every 1 fructose unit, and a great supplement option is High 5 Energy Source 2:1.

Carb repletion

Once you have recovered those carb stores immediately after the event/training you then need to replete you glycogen stores for the next day’s activities. The best way to do this is to have a starch based meal that evening consisting of maybe some sweet potato mash, followed by a banana sandwich (granary bread), and a serving of rice, pasta or porridge oats approx 1-2 hours before bed.


Metzger, J. (2008). Carbohydrate Super‐compensation: Fact or Fiction? Understanding the Truth Behind ‘Carb‐Loading. Retrieved July 25th, 2012, from

Minehan, M. (2004). Department of Sports Nutrition, Australian Institute of Sport. Carbohydrate Loading. Retrieved July 25th, 2012, from

Tipton, K, D & Luc van Loon, (2013). Nutritional Coaching Strategy to Modulate Training Efficiency. Sodium Bicarbonate. Karger.

About the Author

Job Role Qualified Dietitian and Sports Nutritionist Qualifications BSc (Hons) Sports Science | BSc (Hons) Dietetics Tom has always participated in sport both recreationally and competitively which led to an unquenchable thirst for information on anything health, nutrition and fitness. After leaving school Tom went on to play for a football academy during which time he studied Sport and Exercise Science. From here he went on to study a BSc (Hons) Sport Science at UEA followed by his second BSc (Hons) degree, this time at the University of Hertfordshire studying Dietetics. Tom has worked in the fitness, educational and clinical nutrition industry starting out at David Lloyd Health and Leisure Clubs. He then went on to work as a Dietitian (RD) in the NHS, during which time he conducted clinics for healthy eating, weight loss and weight gain, as well as specialised consultations on Diabetes, IBS and Coeliac disease to name a few. He has vast amounts of experience at devising diet plans and supplement regimens, as well as working in the community with schools and competitive athletes. As Head Nutritionist and Supplement expert at Discount Supplements Tom is here to provide current and evidence based health and nutrition information to help you reach your health and fitness goals!
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