What fuel will optimise your sports performance/daily living?



“There is always space for improvement, no matter how long you’ve been in the business.”

Oscar De La Hoya

In today’s sporting environment, especially at the elite level, there is always room to improve. Athletes hire numerous Sport Scientists, Strength & Conditioning coaches and doctors to help gain what may only be 0.1 of a second.

While there is a lot of pretty technical preparation done to gain that edge, a significant amount of what is done to gain that edge is focused on nutrition and hydration strategies pre, during and post exercise.

Moreover, while the start of this blog is quite intense, the hard work has been done by others before us, and you don’t need to have lots of equipment to experiment. Simply take some of what is said here, some of your own research, and try it yourself.


So, what constitutes ‘fuel’?

  • Food;
  • Fluids;
  • Supplements (to an extent).



Foods are broken down into two main segments; macronutrients; and micronutrients.


  • Proteins;
  • Carbohydrates;
  • Fats.

Let’s regard these as the cornerstone for optimising sports performance. These nutrients are here as a fuel source, for muscle repair, and for recovery. Without these, there will be no athlete.


Micronutrients consist of:

  • vitamins;
  • Minerals.

While only needed in small amounts, these are important for human development and well-being, such as metabolism regulation, heart-rate, and bone density. Clearly these are important for general health, however, they can be crucial in sporting events, too.



These may come in the form of:

  • Water;
  • Isotonic/electrolyte drinks;
  • Caffeine drinks.

However the focus will be the first two, as I have already posted about caffeine and its effects on performance.

Fluids are the reason we remain hydrated, and as you may expect, are imperative for sports performance, and life longevity!

Food as fuel

To understand how we use food as a fuel, and therefore energy, you need to understand how we measure energy expenditure in people.

There are two main methods:

  1. Indirect Calorimetry;
  2. Respiratory Exchange Ratio.

I won’t delve into these too technically, however I will explain the general sentiments of both.

1. Indirect Calorimetry

This method measures heat production. The word ‘calor’ means hot in Spanish, and ‘metry’ is ‘the measurement of’ (not a Spanish derivative).

A general concept to understand is that whenever you are moving around, there is biochemistry occurring within your body, and heat is being produced.  SO, the idea is that if you know how much heat you are producing, you can then work out how much energy is being expended doing different tasks.

Interesting statistics:

  • Only 40% of the energy we produce is used to produce ATP (our initial energy source, among others);
  • The other 60% turns into heat.

direct calor

How Indirect Calorimetry is measured↑


2. Respiratory Exchange Ratio (RER)

This method works out energy expenditure through gaseous exchange in respiration during exercise. We use mouthpieces and a bit of kit called a Douglas Bag to collect the gas, and use an unnecessarily complicated equation (called the Haldane Transformation, for those interested…) to work out a persons energy expenditure.

The calculation will produce a figure between 0.7-1.0.

  • A produced figure of ~0.7 means the person’s main fuel source were fats;
  • A produced figure of ~1.0 means the person’s main fuel source were carbohydrates;
  • RER does not take into account the use of proteins as a fuel, as they only constitute for ~5% of energy in the body. They are mainly used for cell repair in muscle fibres, and ideal for post-exercise consumption.

As a general rule, although over-simplified, you can say that the lower the figure, the fitter the person is.

douglas bag

OK all the complicated garbage is out of the way. I am going to attempt to explain why these numbers and names are so important when trying to fuel for your sport, and will hopefully add some logic to why you might use different fuel sources.

Putting all things ‘food as fuel’ together…

As discussed, there are three main macronutrients, and they each produce a certain amount of energy:

  • Protein= 4 kcals of energy/g;
  • Carbohydrates= 4 kcals of energy/g;
  • Fats= 9 kcals of energy/g

From this, you might ask “why doesn’t everyone just take in fats before exercise, as it produces the most energy per gram?”

If you are thinking that, good.

However, the answer is not so simple…

Fats are much tougher for the body to break down, and to be used as energy compared to carbohydrates. To put this into context, it takes 23 oxygen molecules to break down a gram of fat, while it only takes 6 oxygen molecules to break down a gram of carbohydrate.

Which do you think your body will use more readily during exercise? Carbs.

When exercising, you are obviously breathing harder and therefore taking in lots of oxygen and carbon dioxide. As intensity increases, your body is not able to process oxygen efficiently enough to continue to break down fats, and therefore resorts to using carbs as fuel (IE fat utilisation and intensity have an inverse relationship) (Romjin et al., 1993).

There is only a tiny portion of the population who are actually ‘fit’ enough to oxidise (utilise) fats efficiently as a fuel. Super endurance athletes such as Mo Farah, Chris Froome and X-Country skiers are just about able to do so. It is possible, but you have to be incredibly well conditioned.

x country skiers

Do not be disheartened though… Let’s work with what we have got, rather than what we haven’t.

As a tip for the general population, if you are about to take part in strenuous exercise, that requires an effort of ≥ 7/10 from you, eat carbs before doing so. This would imply you are working at a heart-rate that pretty much inhibits fat utilisation as fuel. Bircher & Knechtle (2004) tested fuel utilisation in obese people and athletes as subjects, and found that the highest intensity for fat oxidisation in the obese subjects was 65% of VO2peak, compared to 75% of VO2peak in the athletes.

I’ve said it before, BUT the fitter you are, the more able you are to process and utilise fats as fuel.

Putting all things ‘fluid’ together…

Being hydrated throughout the day is critical for the maintenance of bodily functions, but also when preparing to take part in any sort of exercise. You often hear coaches say “start drinking water the day before an event”, which is not a bad practice to get used to.  However, some studies suggest that it only takes 45 minutes to go from partially hydrated, to fully hydrated (Logan-Sprenger et al., 2013).

The process of dehydration refers to both hypohydration (dehydration induced prior to exercise), and exercise-induced dehydration. Both have negative affects on both exercise performance, and everyday life.

Effects of dehydration:

  • Hypohydration (dehydration before exercise) has a negative effect on aerobic performance. Shown by Armstrong et al. (1985) as participant volitional fatigue (point at which you cannot do another rep/run anymore), decreased significantly during mean treadmill run times;
  • Exercise induced dehydration ALSO decreases aerobic performance, and increases core temperature (Barr, 1999);
  • Barr, 1999 also states that dehydration may induce more utilisation of carbohydrates, and therefore use up their stores much more quickly;
  • Dehydration also effects cognitive performance, shown by Grandjean (2013), as it was demonstrated that decrements in physical, visuomotor, psychomotor, and cognitive performance can occur when there is a 2% loss in body-water due to heat, water restriction, or physical exertion.


As demonstrated, dehydration can negatively effect performance, and while it might not directly be seen as a fuel, it may make your body utilise other fuels earlier than necessary.

If it makes it easier, you could also see it as a ‘hygiene’ factor (IE, the body expects you to be hydrated, and if it isn’t, it reacts badly).

Fluid as fuel…

  • Isotonic drinks (Lucozade, Powerade, Gatorade): Contain carbohydrates, and therefore when ingested, will act as a fuel source. Can be taken pre, or even during events to try increase time to fatigue. Interestingly, you may not even have to ingest the drink for it to be effective. Carter et al. (2004), displayed that just rinsing maltodextrin (carb supplement) around your mouth like a mouthwash, induced better performance in a 1hr cycling time trial.
  • Creatine supplementation: short-term supplementation during training regimes of 5g creatine in water, can induce serious benefits. Izquierdo et al. (2001), found that creatine increased both time to fatigue (∴↑endurance), and maximal strength. Your Phosphocreatine system is one of your first ports of call as a fuel, and it helps re-synthesise ATP (another main energy source) stores, which is why creatine supplementation is so effective.


Sport Specific fuel utilisation strategies

Hopefully, after the following you would assume that all sports are NOT fuelled the same.

I am going to put these strategies into categories:

  1. Ballistic/explosive events (MMA, Wrestling, weightlifting);
  2. Endurance events (cycling, running);
  3. Mixture (football, rugby, tennis)**;
  4. Low intensity (cricket, golf)

** Mixture implies that at many points there will be a need to move explosively, but you will also be running around sub-maximally.

Moreover, if you are about to undertake an intense training block, you need to be in a caloric surplus (eating more than you burn), as the exercise will make you burn a lot of calories. In lots of sports, losing weight is not beneficial!

1. Ballistic/Explosive events (MMA, wrestling, weightlifting)

  • High carbs (40-50%);
  • high protein (~40%/BW x 1.5-2);
  • Low fat (~10/15%);
  • Supplement 5g creatine a day, during training blocks.


2. Endurance events (cycling, running)


  • High carbs (50%);
  • Moderate protein (30%/ BW x 1.2-5);
  • Moderate fats (20%);
  • Supplement 5g creatine a day, during training blocks.

Advanced (consistent runner, looking for new challenge):

  • High fat (50%);
  • Moderate protein (30%/ BW x 1.2-5);
  • Low Carb (20%);
  • Supplement 5g creatine a day, during training blocks.

Note- it has been recommended to begin experimenting with this diet well before any competition. Our bodies are so used to carbohydrates, that the high-fat adaptation period can take up to 6 weeks.


3. Mixture (football, rugby, tennis)

  • Moderate/high carbs (35-50%);
  • high protein (~40%/BW x 1.5-2);
  • Low/moderate fat (~10/25%);
  • Supplement 5g creatine a day, during training blocks.

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4. Low intensity (Cricket, golf)

  • Low carb (20%);
  • Moderate protein (30%/ BW x 1.2-5);
  • High fats (50%);

With low intensity exercise, your body is able to properly oxidise fats, therefore in these sports, you can afford to drop carbs and increase fat intake!


Firstly I know it is a lot to take in, but if you can grasp these fairly basic principles (all the hard research has been done already), with persistence and determination, you can take your training and performance to a totally new level.

Food comes first, training second!

“To eat is a necessity, but to eat intelligently is an art.”

Francois de La Rochefoucauld (1613-1680)

On a side note, if you are curious what your daily caloric intake should be, google is amazing. “Macronutrient calculator” typed in on google will be your saviour…

However, if you happen to know your body-fat percentage, you can try the Cunningham Method:

Lean body mass x 22 + 500.

If you have any questions, please do not hesitate to contact me on Instagram (@thestrength_student) or my email, in the ‘contact’ section of this blog!


The end.










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