Active Travel



How Many Carbs Do You Need For Runners? Should Runner’s Avoid Gluten? Tips from a Registered Dietitian

Apr 4, 2020 | Dietetics, Nutrition, Nutrition for Running | 0 comments

How Many Carbs Do You Need For Runners

Many of us runners love carbs, we know they help us fuel our workouts, particularly our long runs. And they’re crucially in enabling us to get to a marathon finish line. However, since the late 90’s they have been demonised by many as

Luckily, it seems tides are turning. In fact, during this time of lockdown, one of the most googled things is ‘how to make sourdough?’! And it sometimes feels like supermarket rice and pasta shelves are never going to be fully stocked again (read this post on how to eat well even when you can’t buy your usual groceries).

But this post and accompanying podcast is focusing on carbohydrates and gluten for runners…how much we need, what type and when. I chatted with Registered Dietitian, runner and recipe writer Micah (find her at nutritionxkitchen on instagram and her blog of the same name) and coeliac runner, Lucy (find her on instagram at our_gf_home)

Micah who is a dietitian, a runner and recipe writer, and Lucy, who is an Art Director, a celiac and a runner.

What are carbohydrates? 

Carbohydrates are a macro nutrient, of which there are three main ones: protein, fats and carbs. These macronutrients break down to provide your body with energy to function, otherwise known as calories. Most foods contain a mixture of macronutrients. Carbs are our main (and preferred) energy source. It is stored in our muscles as glycogen. When these stores are depleted, stored fat can be burned to provide energy.

When we talk about carbohydrates, it’s not just bread and pasta, but fruits, veg, legumes and pulses too.

‘When athletes compete in endurance events, it is carbohydrates, not fat-based fuels that are the predominant fuel for the working muscles, and carbohydrate, not fat, availability that become rate limiting for performance.’

Hawley and Leckey, Sports Medicine, 2015

Typically, when we think of carbs, the first things that come to mind are bread, potatoes, rice, oats and grains; but fruit, vegetables, beans and legumes are also great sources in your diet.

Simple carbohydrates (such as glucose and fructose) are broken down and absorbed quickly into the bloodstream to give a fast energy boost. Real food versions are found in fruit, milk, yoghurt, cakes and juices.

Complex carbohydrates, also known as polysaccharides, are made up of multiple sugar groups linked together. This makes it harder for the body to break them down, slowing down the release of energy into the bloodstream and giving you a longer-lasting energy burn. Examples are potatoes, quinoa or wholegrain rice. These are the types of carbs you want to have with most meals to keep your energy levels stable throughout the day, fuelling you through your workout, job, social life and whatever else you tackle.

They are also key for longer runs/workouts. Typically in combination with simple carbohydrates to replenish glucose when your stores start to get low. An example would be having a bowl of oats and a banana for breakfast before a 14- mile run. Then consuming an ‘energy gel’ at 7 miles to keep you powered up to the end of the run.

While simple and refined carbs (typically ‘white’ versions, such as white bread and other processed foods) have got a bad reputation, there is a place for them in a runner’s diet. In particular, simple carbs are beneficial post-workout /race for a quick refuel, and in combination with complex carbohydrates (usually wholegrain) pre-race for a mixture of quick- and slow- release energy!

What types of carbohydrates should we be looking for at different times of the day when training?

We’re looking for more of the ‘simple carbs’, those that are broken down and released into our blood stream more quickly, to consume closer to our race, and during the race itself.  These can be things like gels, sweets, fruit etc – quick sources of energy. Complex carbs, that take longer to break down. We want to be eating when we have three to round hours at least before a race. For instance, porridge and beans, food with a little bit more fibre to them (but not too much!). This is when you’ll opt for more of the ‘white’ carbs rather than wholegrain.

How many carbs should we be getting a day as runners?

It depends on the length and intensity of your runs and how much you weigh. But on average while training, 10 grams per kilo of body weight.

So for a 70kg runners, that’s about 700g of carbs daily (especially important when you’re ramping up the milage). You’re probably looking for between 45-65% of your total intake to be from carbohydrates (fruit, veg and wholegrains).

How Many Carbs Do You Need For Runners

When should athletes choose Low vs High GI foods? 

Often abbreviated to GI, the glycaemic index of a food is a ranking of how quickly it is converted into sugars, and therefore the effect it has on your blood glucose levels.

A high GI means a food can be quickly digested, causing a spike in blood glucose (and potentially subsequent dip if not eaten in combination with foods that are rich in lower GI carbohydrate, protein or fat). Low GI foods and drinks have a longer digestion time, gradually increasing blood glucose, helping to keep us full over a prolonged period and hopefully avoiding that ‘sugar crash’.

As you might imagine, most of the time low GI foods are best, helping us fuel our days and runs/workouts. However, pre- or post-workout /race, picking a mid- to high-GI food or drink can help with topping up carbohydrate and muscle glycogen stores (refuelling!).

What about fibre? 

Fibre is a type of carbohydrate. It comes from all our plant-based food – fruit, veg, beans, pulses, lentils, legumes, whole grain carbohydrates such as brown rice and brown pasta. Fibre is basically what forms the bulk of our poop. We need to make sure we are getting enough fibre so that we can pass bowel motions regularly. So that we are not constipated or having diarrhea. U.K. guidelines suggest we should be aiming for 30 grams of fibre everyday.

Soluble fibre is easily digested by our gut bacteria and is found in oats, fruits, legumes and vegetables. As well as forming natural gels that soften stools, it may also help maintain stable blood glucose and healthy cholesterol levels.

Insoluble fibre adds bulk to your stool, making it easier to pass and is found in whole grains, vegetable skins, nuts and seeds. Most fibre-rich foods typically contain both kinds.

There’s a whole blog/podcast on Fibre & gut health here. 

Asics pullover jumper

Is it possible to eat too many carbs?

Of course it’s possible to eat too much of anything, if you ‘overeat’ carbohydrates and your body will just store them as fat for later energy, and it can also have an impact on your blood sugar levels (blood glucose).

Eating too many carbs or too much of any macro nutrient, means you run the risk of missing out on eating the other things your body needs to function properly, so we might not get enough protein, fat or the other vitamins and minerals that are found in those other foods.

Choosing carbs which will keep us full, so whole grains or high quality carbohydrates – whole grain breads, brown rice, quinoa, legumes, full fresh fruits instead of juices.

What kind of carbs should we be eating the night before a long run?

We have to think about timing: the night before a long run or big workout, you want to get some quality carbohydrates, a source of protein and fats. Really, looking for a balanced meal that’s a little bit higher in carbs.

But that doesn’t mean you need to have a full plate of white pasta and ‘carb load’ that night. Your body has time to digest a balanced meal, the fibre can go through you. So opt for high quality, ideally less processed. For example, a baked sweet potato, a protein source, some veg and a fat source!

But do you think we should carb load before a race?

It depends on how long your race is!

If it is under 90 minutes, like a 5 or 10K, (or half marathon for some!) you don’t really need to carb load. But when most of us go for a half marathon and above, depending on your timings, then you might start talking about carb loading.

That doesn’t necessarily mean a you have to go to the pre-race pasta party. It could just be increasing your carbohydrates slightly over the previous three to six days pre-race in combination with a reduction in mileage. It’s all about a gradual increase in carbs, as simple as an extra sports rink or an extra smoothie. Try to be more mindful of the carbohydrates that you are eating, maybe including one extra carbohydrate-rich snack a day for the week leading up to the race is enough.

But keep in mind that carb loading studies show that it increases your performance by about two percent! Carb loading won’t turn you into Mo Farrah! Getting the right carbohydrate amount pre and doing the race   will make sure your body has enough energy to finish that race!

The key is to practice on your long runs so that you know how your body will react on race day!

What about carbohydrates on race day itself? 

There’s a whole blog and podcast on this topic but a basic overview is that we should be aiming for about 30 to 60 grams of carbohydrates per hour while we’re running as our bodies can’t digest more than that.

Some people fuel every 30-45 mins, some every 3-5 miles, its whatever works best for you. And this can be ‘real food’ such as dates, a fruit bar, potatoes, or something like a gel, sweets or a sports drink.

Do remember that real food and sweets (like Haribo or Jelly Babies) don’t actually have as many carbs as a fortified gel, so you may need quite a few of them. Do read the back of your sweet package to know how many carbs are in them, but also to make sure there is no sugar alcohol in the product, as that can wreak havoc on your gut!

How Many Carbs Do You Need For Runners

According to a recent study, 41% of athletes are following a gluten free diet (that’s four times higher than the general population!), whilst in actual fact, only 13% of them need to do so medically. The other 28% of those in the study had self-diagnosed their gluten sensitivity, or were following a craze/online advice, perhaps believing that they would see performance benefits by cutting out gluten. However, there is currently no evidence to support this.

What is gluten?

Gluten is a protein found mostly in wheat, although it is also found in barley and spelt. Celiacs have an immune response to gluten. It’s not that they just feel a little bloated, a little ‘off’. But the body has an immune reaction to gluten. You can also be sensitive to gluten but that is not celiac disease.

What are the signs and symptoms of Coeliac Disease? 

The only way to confirm a diagnosis of coeliac disease is through a blood test or biopsy. It’s worth speaking to your doctor if you experience any persistent unexplained gastrointestinal symptoms, prolong fatigue, unexplained weight loss or faltering growth in children/teens. Mouth ulcers that are severe or persistent, unexplained iron deficiency, vitamin B12 or folate deficiency, IBS or an autoimmune thyroid disease.

Should we be avoiding gluten, even if we don’t suffer any ill effects after eating pizza or cake, for example?

No. It is important to know and tune into your body. If you feel bloated, ask yourself what prompted that? But if you are fine with gluten, don’t jump on that bandwagon. Having a gluten-free sandwich just isn’t the same! A lot of the gluten-free products are made with ingredients you might not choose to have or find in your cupboards. A lot of gluten-free products are less nutritious than their gluten-containing counterparts. They can contain a lot of sugar or binding agents – make sure to read the back of the pack!

What are your favourite natural gluten free alternatives?

Rice, potatoes and sweet potatoes are great, as are quinoa, buckwheat, millet and teff.

There is is an important differentiation…something can be gluten free, but can’t necessarily be classed as suitable for celiacs. For example, if you go out for pizza, it has to be in a separate oven, on a tray not used by regular pizza. Some restaurants like Pizza Express have their own section for celiacs. Celiac UK are great, they have an app and a book and a helpful website.

Top Tips for newly diagnosed celiacs?

Look for other people who are celiac, ask them for advice. It’s so helpful and you will be surprised how common it is. There is an amazing community on Instagram to find recipes and places to be, discuss symptoms and not feel so alone. I had awful acne, not something you would think be related to your diet and that cleared up. Keep reading the packets. The amount of stuff in your cupboard which has gluten in it is incredible. But there are a lot of alternatives: Tamari is a good alternative to soya sauce for example.

It is important to know that for a celiac, there is no cure. The only treatment is a fully gluten free diet.

Let me know if you have any other questions about carbs or gluten… or any nutrition advice for runners. My cookbook COOK EAT RUN features both high and low GI recipes as well as those naturally Gluten Free for those that need a GF diet! You can download, subscribe and listen to the COOK EAT RUN podcast on iTunes, Spotify or wherever you listen to your fave podcasts.

Previous episode include:

Marathon Fueling : What to eat on the Run 

How to Avoid Runner’s Trots: Fibre and Gut Health 

Post Run fueling: What to eat after a run 


Submit a Comment

Your email address will not be published. Required fields are marked *