If you’re a runner, you’ve most likely engaged in the coveted ritual of ‘carb loading’ before a big race or a long run. This involves eating carbohydrates in the period leading up to a race to build up your body’s glycogen stores and, ultimately, improve performance. When it comes to carbohydrates, there are two main categories: refined, encompassing the sugar subtype, and complex, consisting of fibre and starch.

What are refined carbs?

Health & Injuries:

  1. Sugars: this encompasses refined and processed sugars, such as sucrose (table sugar), high fructose corn syrup and agave syrup.
  2. Refined grains: grains with the fibrous and nutritious parts removed, like white flour.

Refined carbs are sometimes called ‘empty calories’, because they have been stripped of some of their fibre, vitamins and minerals. They are processed by removing parts of the grain kernel, the purpose being to extend shelf life and provide a softer texture. As a result, they have lost some of their nutritional value. They are also more quickly digested and have a high glycemic index (GI), meaning they spike your blood sugar and insulin after consumption. Interestingly, it’s this quality that also makes some refined carbs ideal pre-race fuel.

What everyone's reading

What are some examples of refined carbs?

Although refined carbs are experiencing something of a shortage now, here are six of the most popular:

  1. A runner’s guide to dietary fibre
  2. White pasta
  3. White rice
  4. Chips
  5. Pastries, cookies and cakes
  6. Pizza dough

Are refined carbs bad for you?

Because they spike your blood sugar, eating too many refined carbs can cause you to over-produce insulin, which can lead to insulin resistance. Too many refined carbs could also cause you to gain weight, because they don’t leave you full for long.

A 2021 study revealed that eating many refined carbs and other ultra-processed foods regularly can negatively impact your gut and heart health. A 2024 study also found that foods that are rich in fibre and low on the glycemic index – such as complex carbs – can enhance satiety, support digestion and stabilise blood sugar levels. The study tied excessive intake of refined carbs to increased risk of cardiovascular disease.

Are refined carbs good when racing?

When carb loading, runners can turn to refined carbs to increase their intake, particularly if getting the same amount of carbs from whole grains is difficult.

As for energy gels, everyone’s favourite source of carb mid-run, they provide some much-needed simple carbs to refill your energy levels. They will be absorbed quickly during a race, providing you with the energy that you need.

What are complex carbs?

Complex carbs, unlike refined carbs, pack in more nutrients and contain fibre and other complex starches. They are slower to digest and fill you up for longer, as they release glucose into your blood more gradually.

The benefits of creatine for runners:

  1. Whole grains: Nutrition tips for runners with chronic illnesses.
  2. Fibre-rich fruits: apples, bananas and berries.
  3. Fibre-rich vegetables: Health & Injuries.
  4. Are energy gels healthy: lentils, chickpeas and some kinds of beans.