How-to guide for carb confusion - Women's Running

How-to guide for carb confusion

Author: Chris Macdonald

Read Time:   |  June 24, 2017

Why you need it

You need carbohydrate to maintain your blood glucose levels and replace muscle glycogen lost during training. Keeping your blood sugar level balanced is also essential for reducing the effects of the stress hormone cortisol. In fact, balancing the stress response to high intensity exercise is a central strategy if you’re to ensure adequate recovery and see your performances improve.

Glucose from carbohydrate is stored in limited amounts in your muscles and liver as glycogen and it is this glycogen reserve that could potentially limit the length and intensity of your running performance. This means you should aim to get a regular supply of carbohydrate throughout the day and particularly after any form of exercise.

Strike a balance

Carbohydrates are found in a wide range of foods including fruits, vegetables, whole grains, beans, pulses and some dairy products. Some of these foods release carbs faster than others. These foods tend to have a high glycaemic index (GI). You should typically choose higher GI, and lower-fibre, options before training (such as a banana, yogurt or fruit smoothie) and consume slow-release low GI carbohydrates (such as vegetables, whole grains, beans and pulses) as your main meal of the day or as a post-run snack. Slow-release low GI carbs will keep you fuelled for longer and will also prevent the production of excess insulin, which can disrupt energy levels and lead to weight gain.

Essential energy

Many runners overlook vegetables as a useful carbohydrate source. They are packed with antioxidants to protect against free radical damage as well as B vitamins and magnesium, which are essential for energy production. They are also easy to digest and will not lead to an unhealthy spike in insulin. Conversely, many people are finding grains more difficult to digest and tolerate – often resulting in stomach pains and digestive problems. So experiment to find out what suits you best but focus on nutritional value and avoid refined sugary options that disrupt blood glucose levels.

Time sensitive

When you eat your carbs is just as important as what you eat. Since more complex carbohydrates – such as whole grains, oats, beans and pulses – will sit in your gut and take longer to digest, these low-GI options are best eaten several hours after you’ve run to top upyour glycogen stores and to promote recovery before your next training session. Without sufficient refuelling, your cortisol levels can also rise, which can lead to the break down of lean muscle mass and inhibit repair of muscle tissue.

Pre-run boost

An hour before you run, stick to medium and high GI foods that are easy to digest and quick to absorb. You could try a small banana, a small serving of pineapple, a peeled apple, a small sweet potato, melon or some dried fruit.

Post-run recovery

Aim to eat 20-30g of easy-to-digest high GI carbohydrate with some protein within 30 to 45 minutes of your run. This could be fruit (for example, a cup of berries) in a protein shake. This will help to quickly restore glycogen levels and support recovery.

If you’ve been running for more than an hour, aim to follow this post-run snack with a meal an hour or two later that combines protein (chicken, fish, eggs etc) and liberal quantities of starchy vegetables like carrots, parsnips, squash, potatoes and sweet potatoes.

You may also need several snacks throughout the day to keep your carbohydrate levels topped up. A couple of oat cakes, a fruit smoothie or a cereal bar are all good options. Aim to combine carbohydrates with protein too as this will support muscle repair and stabilise your blood sugar levels.

Daily needs

The amount of carbohydrate you need to consume will depend on how often you’re training. You should aim to get around 50 per cent of your daily calories from carbs. Check out the suggestions on the table below, but remember that everyone is different. Aim to fill half of your plate with vegetables, and include a serving of grains or potato as well as some protein to help reduce insulin spikes.

If you are running for three to five hours each week, your daily intake should be roughly 4-5g per kg of body weight. So if you weigh nine stone (57kg), you would need to consume around 228g-285g of carbs every day. You could easily achieve this by eating a bowl of porridge with raisins for breakfast, a banana with yogurt before training followed by a chocolate milk shake or fruit protein shake after training. Then eat a baked potato with plenty of vegetables as part of a meal later in the day together with a couple of snacks such as fruit or a cereal bar.

Hours of Training

Carbohydrate needs:  grams per kilogram of bodyweight, per day


3-5 per week 4-5g
5-7 per week 5-6g
1-2 hours per day 6-7g
2-4 hours per day 7-8g
4+ hours per day 8-10g


Chris Macdonald

Editor-at-Large, Women's Running

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