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Triathlon Training Nutrition

Maximise Your Training Adaptations

Getting your triathlon training nutrition right will make all the difference to your performance.

Taking on board the right amount of nutrients at the right time is vital in order to:

  • Fuel training sessions and races
  • Allow adaptation and recovery from training
  • Reduce fatigue and muscle damage
  • Reduce risk of illness
  • Maintain a healthy body weight

Thinking through what you eat and when and putting together a good triathlon training nutrition plan will help you get the most out of yourself.

If you have any questions about your triathlon training nutrition then please just ask us.

How Much Do I Need To Eat?

The amount you need to eat will depend on your body weight, metabolic rate and the amount and intensity of training you do.

In terms of triathlon training nutrition, what you need to eat and drink on any particular day will be influenced by the duration of the session, the weather conditions during your session and when your next training session is.

It is possible to have your metabolic rate measured in a lab, and a physiology assessment can also give you an idea of how much carbohydrate and fat you use for a given exercise intensity. This can help you put together a suitable triathlon training nutrition plan.

There are also various calculations you can use to get an estimate of your daily energy expenditure. You can find these on the internet. However bear in mind that these are estimations. One of the most well known is the Harris-Benedict equation:

English BMR Formula
Women: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years) 

Men: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in year)1

Metric BMR Formula
Women: BMR = 655 + (9.6 x weight in kilos) + (1.8 x height in cm) - (4.7 x age in years)

Men: BMR = 66 + (13.7 x weight in kilos) + (5 x height in cm) - (6.8 x age in years)

To determine your total daily calorie needs, multiply your BMR by the appropriate activity factor, as follows:

  1. If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
  2. If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
  3. If you are moderately active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
  4. If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
  5. If you are extra active (very hard exercise/sports & physical job or 2x training): Calorie-Calculation = BMR x 1.9

You will burn lots of calories through your training. Nutritional strategies to replace these will very depending on whether you want to maintain a stable weight, or reduce your body fat levels. Knowing your daily calorie needs can be useful, particularly if you are trying to lose weight or are struggling to maintain a healthy weight due to the volume of training you are undertaking.

What Do I Need To Eat?

There is no magic diet. The main aim should be to eat healthily, with a good balance of nutrients.

Select good quality foods, those that are nutrient dense.

Examples of nutrient dense food choices to include in your triathlon training nutrition plan:

Examples of nutrient dense food choices to include in your triathlon training nutrition plan:

Carbohydrate Protein Fat


100% juice

Lean beef



Soy foods

Vegetable oils



Before Training

Your triathlon training nutrition plan starts before you begin training! You want to make sure that you start a training session with plenty of energy and well hydrated. If you are doing early morning sessions, there will be the temptation to get those extra few minutes in bed and miss breakfast. However you need to take some food on board to give you energy for the session. So:

  • Try to have a glass of water, fruit juice or smoothie first thing. This will help you rehydrate after your night’s sleep.
  • A low fat breakfast containing carbohydrate and protein is ideal.

Here are some examples of pre-training breakfasts.

  • Porridge with milk and dried or fresh fruit
  • Cereal with semi-skimmed milk and a banana
  • Tomatoes, mushrooms and a poached or scrambled egg
  • Toast or bread with low fat butter/margarine and jam, and a glass of milk
  • Fruit, low fat fruit yoghurt and some mixed nuts and seeds
  • Lean bacon and wholemeal toast and fruit.

Tea and coffee are fine to drink with your breakfast. Their diuretic effect is minor and the caffeine can help wake you up.

If there’s no time for a proper breakfast or you can’t stomach eating too close to a session, then milk based drinks such as smoothies, fruit, fruit juices and cereal bars are all good options.

Enhancing Fat Utilisation

When you exercise you use a mixture of fats and carbohydrates to fuel this.

Triathlon is an endurance sport (yes, even the sprint distance!) and so you want to be as good at using fats as you can. This is because you have a lot longer lasting supply of fats in your body than you do carbohydrates.

Fats only supply energy quite slowly though, so if the exercise intensity is high, you need to get a greater supply of energy through carbohydrates, which are metabolized more quickly. At the lower exercise intensities, the better you are at using fats as a fuel, the longer your carbohydrate stores will last.

Training at the right intensity (an intensity that uses mainly fats as a fuel, ie fairly low intensity) will improve your ability to use fats as a fuel.

However, there is a way of enhancing your use of fats through nutritional strategies.

  • Carbohydrate intake before or during exercise stimulates the use of carbohydrate during the exercise, inhibiting fat use.
  • Conversely, eating high fat foods stimulates fat use and inhibits carbohydrate use.

But beware, carbohydrates are needed for higher intensity exercise, and eating a high fat diet has been shown to inhibit carb use and so limits performance.

In practice this would mean you could ride/run all day at a low intensity but wouldn’t have anything in your legs if you tried to up the pace.

So the answer is to train in a fasted state.

In practice, this would ideally be a morning session where you have got up and trained without having breakfast. What this does is it enhances your fat use, but without impairing your ability to use carbohydrates.

This method is also good if you are trying to lose weight, as training in this condition stimulates the use of peripheral fat stores.

Don’t do this for all your sessions though!

Training in a fasted state is fine for long rides/runs, but if you want to do any sort of intensity in the session, eg intervals, tempo session, hill climbs etc, you will need carbohydrate to do this effectively. If you don’t, the quality of your session will suffer.

So as a rule of thumb:

  • If you are training long and slow, you could do this on an empty stomach to promote fat utilization.
  • If you are doing faster or higher intensity sessions, make sure you have had a meal high in carbohydrates beforehand.

Training in a fasted state is something to seriously consider doing, particularly as one recent study showed that the improvements in endurance performance were much higher from a bout of training in a fasted state compared to exactly the same training in a fed state.

During Triathlon Training

Nutrition can have a real impact on the quality of your sessions. For shorter (< 60 - 90 minute) sessions, you should not need to take on any extra energy. However if you are doing a long one (for example a long >90 minutes training ride) then it is essential you take some food with you. You need to keep topping up on carbohydrates so that you don’t run out of energy. Things you can take with you to easily eat in action include:

  • Sports/energy bars
  • Energy gels
  • Jelly sweets
  • Dried fruit
  • Sports drinks
  • Sweet biscuits

Sports Drinks

Sports drinks play a big part in triathlon training nutrition. They are an ideal way of getting some fuel in the tank and also keeping you hydrated during a training session.

You will be able to find a wide variety of commercial sports/energy drinks. These will all vary in their content, so make sure you read the label. The concentration of carbohydrates will vary, making them more useful in certain situations than others. Most will also contain electrolytes (salts) to replace those lost in sweat.

Carbohydrate concentration When to Use Purpose
2 – 4% In hot conditions, session shorter than 1 hour Maximise rate of water uptake, but low in carbohydrate. Fluid replacement more important than energy provision.
6 – 8% During training Easily digestible (carb concentration is ideal for your body to absorb), allows good uptake of fluid.
>8% After training High carbohydrate availability, water not absorbed easily. Emphasis on replacing energy rather than fluid.

For a recipe to make your own drink, and to find out more about hydration read our page on hydration for triathlon training.


Protein is an essential nutrient in the diet. It is required for growth and repair.

However in terms of triathlon training nutrition, this is usually not something you need to worry about. Generally speaking, if you have a well balanced diet you are likely to be eating enough protein. 1.0 – 2.0g/kg body mass per day is the generally recommended amount.

If you are in a period of very heavy training (eg 30+ hours per week, back-to-back sessions etc), then you might need extra protein to cover a small proportion of the energy costs of your training and to assist in the repair and recovery process after exercise. Younger, adolescent athletes will also need more protein.

The only time you are at risk of not taking on enough protein is if you are restricting your diet. If this happens, you will lose strength and power, and will not make optimal gains from training.

Studies have shown that athletes eating to meet their energy requirements are usually consuming protein well in excess of 2.0g/kg body mass per day.

Therefore there is little evidence to support trying to work a high protein diet into your triathlon training nutrition plan, or taking protein supplements.

Many protein supplements are very expensive. They also tend to provide very large amounts of protein and little in the way of other nutrients. Good alternatives to protein supplements include homemade fruit smoothies, liquid meal supplements, or try adding 20 g skim milk powder to regular milk.

Estimated protein requirements for athletes:

Group Protein intake (g/kg/day)
Sedentary men and women 0.8 - 1.0
Elite male endurance athletes 1.6
Moderate-intensity endurance athletes 1.2
Recreational endurance athletes 0.8 - 1.0
Female athletes ~15% lower than male athletes

Vitamins And Minerals

Many athletes take multi-vitamin supplements. Research studies have looked at the effects of these on performance, recovery, immune function and so on. The general consensus with regards triathlon training nutrition is that whilst these can have a positive effect, if you have a healthy, balanced diet there is no need to take this sort of supplement.

Of course, if you are struggling to eat properly then they can be helpful, but cannot on their own replace the benefits of a healthy, balanced diet.

Staying Healthy - Immune Function

The risk of getting colds and coughs is elevated after a hard endurance training session or a race. If you’re not eating well and maybe your sleep isn’t great either, then this will add to your chances of picking up an infection. The load on your body can be high during intense triathlon training. Nutrition can play an important role in keeping you healthy.

Supplements such as vitamins and minerals have the potential to reduce the risk of illness however studies have not found these to provide universal protection.

Most recently, studies have shown that taking on board enough carbohydrate during and after a session reduces the amount that your immune system is suppressed.

As well as improving immune function, there is some evidence to suggest that carbohydrate can influence injuries. Studies have shown that people training with low muscle glycogen levels are more likely to sustain muscle damage. Co-ordination may be impaired which could explain the increased injury rate. So getting your triathlon training nutrition right could even help you stay in one piece!

Top Triathlon Training Nutrition Tips For Avoiding Illness:

  • Eat a snack containing carbohydrate and protein as soon after training/racing as possible.
  • Eat from a wide variety of foods and consider a daily multi-vitamin and -mineral supplement to ensure that your diet always has an adequate supply of the nutrients needed to support immune function
  • Take in a little extra vitamin C during periods of heavy training and a week or two before and after competitions, as this may give your immune system an added boost
  • Put yogurt, yogurt drinks or other products with certain active cultures on your shopping list. These beneficial microbes may help support keeping your immune system healthy.

Take-Home Triathlon Training Nutrition Tips

  • Before training: 2 – 3 hours before, snack high in carbohydrates, unless a long, easy session, where doing it in the fasted state would enhance your ability to use fats as a fuel
  • During a long workout: 6 – 8% carbohydrate sports drink, energy gel/bars, dried fruit, sweets, aiming for 1g per kg bodyweight per hour.
  • Afterwards: 1 – 1.2g of carbohydrate per kilogramme body weight as soon as possible after your workout, ideally combined with protein.

Nutrition is also key for optimising your recovery.

For advice on how to get the most out of your recovery and optimise your adaptations to training read our recovery nutrition page.

Hydration also plays a key role, particularly in races in the heat. Read our hydration page for top tips and the latest thinking on hydration strategies.

Got a question about your triathlon training nutrition? Then ask us!

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