Everything you need to know about nutrition for runners
When it comes to a runner's diet, it seems that everyone has an opinion. But often, this opinion is based on what we can term n=1 – that is, an individual runner's personal dietary experience, or simplified science that considers only fuelling and recovery.
Of course we need fuel to move and survive, but the human body is more than a machine. Simplifying what we eat as fuel and treating our stomachs as tanks ultimately creates an idea that what you eat as ‘fuel’ will allow you to run a set number of miles. Ultimately, it’s more simple than energy in and energy out. The composition of your diet, timing of nutrients and quantities it takes to support both your running and the intricately essential biological processes of your body are key in considering how you nourish yourself.
Making the right nutritional choices is linked to the maintenance and improvement of running performance, as well as your overall lifestyle. Implementing choices based on a runner’s diet keeps you motivated and healthy, but the timing of your nutrition is integral to maintaining your hormonal balance, as well as supporting your bone health and immune system.
What is the best runners' diet?
So, what are the right nutrition choices for runners? Unfortunately, it’s not a list of right and wrong rules to follow. Rather than turning this diet into an obsession to live by, think of it as information to empower your choices to benefit your running - and your day-to-day diet, too.
Let's talk about carbs
Starting with the most critical component for exercise: carbohydrate. Although it’s misunderstood and often demonised in diet discussions, carbs are the cornerstone of a runner’s diet. The body breaks it down into glucose, pulling it from the bloodstream and using it as its primary source of energy.
Your liver and muscles store carbohydrate as glycogen, which in turn is released as energy when your glucose stores are depleted. The glycogen stores in your muscles are the most readily available and quickly released as energy, but the catch – as you may know from long runs and the latter stages of marathons – is that this storage facility is limited. If muscles are inadequately fuelled, it leads to fatigue and poor running performance, which may even increase your risk of injury.
It takes around 500g of carbohydrate to fill your glycogen stores. At most, this will keep you going for 60-90 minutes of running at around 55-75% of your maximum heart rate. The faster you run, the quicker your glycogen stores will deplete, so if you run on most days be mindful that your glycogen stores are always slightly depleted.
With this in mind, it's vital that you plan your carbohydrate intake around your running habits – the amount you need will depend on the frequency, duration and intensity of your training.
Running on empty
Runners can encounter problems when they attempt hard sessions in a deliberately fasted or carbohydrate-depleted state, owing to poor fuelling in the hours or even day beforehand. More issues arise when runners do not feel hungry immediately after a session, as they'll fail to refuel properly and, as a result, compromise their recovery and training adaptation.
Both situations can negatively impact hormonal regulation and even have long-term consequences on your running performance as well as your overall health. Lowered immune systems, decreased bone density and a slower digestive system are all results of these practices.
The hormone factor
Our eating habits and exercise habits can affect a key hormone called ghrelin – our so-called ‘hunger hormone’ – which is mostly produced in the stomach. Our levels of ghrelin rise after we exercise or several hours after we eat a meal, telling us we need to refuel. When ghrelin is high, levels of leptin – another hormone – are low. Both hormones will return to normal levels when our energy demands are met. However, if a runner continually fails to fuel properly after a training session, intentionally or unintentionally, leptin levels stay low. Chronically low levels of leptin encourage the body to preserve energy, meaning you burn fewer calories and store more fat.
So – in simplified terms– while runners may think that running will enable them to lose weight, the reverse can happen. This explains why some runners, even when they restrict calorie intake or increase training, still don’t achieve the body composition and weight goals they would expect.
Keeping fuelled for runs
For runs that last for longer than 60 minutes, aim to consume 30-60g of carbohydrate per hour for the first three hours, and increase the amount to 60-90g of carbohydrate per hour if you’re still going after that. This carbohydrate can be in the form of sports products such as energy drinks, gels or bars, or actual food items such as bananas, cereal bars or sweets. If you're running far and wide on varying terrain, you may prefer to snack on foods such as boiled, salted potatoes, noodle soup or even pizza.
Fuelling best practice
Gastric distress – including runners' trots – is one of the most common issues faced by runners when they take on fuel mid-run. This problem means that some runners avoid fuelling altogether during long or intense runs, despite the need for them to keep their carbohydrate stores in check. Though it may seem counter-intuitive, eating something small, such as a banana, or drinking fluids to replenish electrolytes may resolve this problem. In addition, proper hydration and altering your pace are equally helpful.
It’s a common notion among runners that they avoid fuelling during runs because they want to “save” their energy for later. But this disrupts the body’s optimal performance and recovery. Runners, instead, should be fuelling before, during and after their runs because it in turn helps with satiety and appetite.
Mid-run fuel should be in the form of glucose and fructose. While the body can absorb around 60g of glucose and 30g of fructose per hour, some studies suggest this 90g limit could be increased to 120g in some athletes who train their gut – although the sample sizes used have been small and only involved men running at altitude. Whatever you choose as your mid-run fuel, practise running with this until you have nailed what works for you. Mistakes include:
Fuelling too late into your run. To avoid this, start taking on nutrition within the first 30 minutes of your run and then top this up every 30-40 minutes after that.
Taking gels too quickly. Take one gel over the space of 4-5 minutes – not all in one go – to aid absorption and tolerance.
Becoming dehydrated and not replacing fluids and electrolytes, specifically sodium.
How to hydrate
Talking of dehydration, runners should be particularly aware of their fluid intake. It is well documented that proper hydration is important during exercise and especially critical over longer training sessions and events. Along with maintaining good hydration levels, fluid intake during endurance running helps to regulate body temperature (thermoregulation) and ensure adequate plasma (blood) volume – both of which have a direct impact on running performance. Dehydration causes your core body temperature to rise, which in turn decreases plasma volume, increases your heart rate and accelerates fatigue.
Just a 1% reduction in bodyweight through fluid loss can bring about these negative physiological effects. What's more, dehydration can markedly affect cognitive function, compromising your ability to think clearly and make good decisions.
Salt intake for runners
Most runners will produce between 400ml and 2,400ml of sweat per hour of exercise. The average is around 1,200ml per hour, although this varies depending on factors including your age, sex and weight, as well as the intensity of your training and the temperature. While you lose mostly water through sweat, you also lose electrolytes – mainly sodium.
The sodium content of sweat can be anything from 115mg per 1,000ml to more than 2,000mg. Most electrolyte tablets, salt capsules or sports drinks provide 250-300mg of sodium. If you are diluting your electrolytes into 750ml of fluid, this will mean having to consume around 2,250ml of fluid per hour to meet your sodium requirements in longer races, which is hard from a consumption and transportation point of view. A runner who is a ‘salty sweater’ may lose even more sodium than the recommended intake.
So, it’s little wonder that many runners complain of the symptoms associated with low sodium intake and dehydration, such as gastrointestinal distress, nausea, bloating, fatigue, impaired concentration and dizziness. In fact, the biggest cause of mid-run stomach issues is related to sodium imbalance – not sports nutrition gels or bars. If you are dehydrated and consuming glucose, it becomes highly concentrated in the gut. This is because blood is being directed away from the stomach to the working muscles, so the gut cannot absorb the glucose quickly enough, resulting in stomach upsets.
I usually recommend that runners take on 700-900mg of sodium per hour during longer training runs and races. This can be a mix of salt tablets, electrolytes, energy drinks and even food if you can stomach it, like salted peanuts and cured meat.
Keeping your sodium levels in balance is important before big training sessions and races, too. I often suggest that runners start drinking electrolytes in the 24 hours before race day to help prevent the issues above.
Fat facts
Not all fat is bad for you. You need some fat in your diet to help absorb the fat-soluble vitamins A, D, E and K, and to provide essential fatty acids that the body can't produce itself. These nutrients are important for recovery and immune health and to prevent inflammation and fatigue. So, fat should be an integral part of your runner's diet.
That said, not all fats are good, either. Eating too much saturated fat can raise levels of harmful cholesterol, which increases your risk of heart disease. Sources include pies, cakes and biscuits, and fatty cuts of meat like sausages and bacon. Saturated fat also encompasses trans fat, which is often found in processed foods. To up your intake of the good stuff, aim to include the following in your diet:
Oily fish, such as salmon and mackerel, for omega-3
Nuts and seeds, including their oils and butters
Sunflower and olive oils
Avocados
I encourage runners to choose good fats over saturated varieties. However, these fats still have a high energy value and should be eaten with that caveat in mind. It's also worth noting that high-fat foods slow digestion, so they should be avoided as an immediate pre-run fuel source.
Protein perks for runners
Protein consists of combinations of structures called amino acids. There are 20 amino acids that together form the building blocks of the body, combining in various sequences to make muscles, bones, tendons, skin, hair and other tissues. Amino acids also transport nutrients and produce enzymes, among other functions.
Eight of the 20 amino acids are essential and must come from your diet. These are found as a complete source – where all essential amino acids are present – in animal proteins, such as dairy, meat, fish and eggs. They are found as an incomplete source – where one or more of the essential amino acids are lacking – in plant-based proteins, such as vegetables, grains, nuts and legumes. If, however, these incomplete sources are combined in the correct way, you can make a complete source of protein. Some good combinations include baked beans on toast, rice and dhal, or a wholegrain bagel with peanut butter.
We in the sports and fitness industry hear a lot about protein, with many believing it is the most important macronutrient for active people. In reality, runners need protein primarily after exercise, rather than as a pre-run fuel source.
Protein has been a huge area of research for many years, with the most recent findings demonstrating how important it is in the recovery phase. During exercise – whether that’s an endurance sport like running or cycling, a team or power sport like netball, football or tennis, or resistance training – there is a higher breakdown of protein in the muscle. While the preference is to consume a large amount of protein in the immediate recovery phase, you should ideally distribute protein-rich foods in your diet throughout the day to help to counteract protein imbalance. The suggested protein consumption for runners and active people is 0.4g/kg of body weight four to six times a day, depending on training load.
For a 65kg runner, this equates to 26g of protein at each serving, which looks like:
4 medium-sized eggs
100g of chicken
100g of red meat
300g of tofu
250g of Greek yoghurt
150g of chickpeas
The small stuff in a runner's diet
Along with macronutrients (carbohydrate, protein and fat), micronutrients are vital for many metabolic processes – and you'll need to get them from your diet. These include:
Vitamins: A, B, C, D, E, K
Minerals: Calcium, iron and phosphorus
Electrolytes: Sodium and potassium
Trace elements: Iodine, zinc and magnesium
Most micronutrients function as co-enzymes or co-factors – that is, they aid enzymes and proteins in their function. For example, the B vitamins are needed for carbohydrate and fat metabolism, while vitamin C, along with zinc, is important for a healthy immune system. Magnesium and calcium, meanwhile, are vital for good muscle contraction. You need all of this 'small stuff' in your diet to stay healthy and run at your best.
Do supplements help?
The research is inconclusive as to whether runners need more minerals and vitamins in their diet. Some studies show that runners have a greater requirement for supplements because their muscles are more damaged by free radicals, which accumulate in response to exercise. (Lifestyle factors, such as smoking, can also produce an excessive amount of free radicals in the muscles.)
When it comes to important nutrients, iron is high on the list for runners. Red meat and eggs are your best sources of iron, as plant-based options – such as green, leafy vegetables, pulses, whole grains and fortified cereals – are harder to absorb than animal products and must be taken with vitamin C to enhance absorption. Dairy is also your best source of bone-essential calcium and phosphorus, although soya products and oily fish are also good options.
Another nutrient for runners to be aware of is iodine. Thanks to the increased consumption of plant-based milks, most of which don’t have added iodine, some people risk being idione deficient, which can lead to metabolic problems. Vegan and vegetarian runners may also need to pay special attention to iron and B12, which can be hard to get from a plant-based diet.
No matter who you are or what your preferences, the quality of your runner's diet is crucial. As an active person, you should be naturally taking in more food to fuel your running – and so long as you consume a balanced, nutritious diet that includes wholegrains, vegetables, meat, fish and dairy, if possible, you should have no problem in getting all that you need.
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