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Avoiding carbohydrates could be costing you your gains (& happiness) – here’s how

Carbohydrates are an essential element to achieving your health and fitness goals, and yet they are often demonised. Let’s take a look at the facts.

28th August 2023

By Zoe Martin

Accredited Practising Dietitian, Sports Dietitian and ANZAED Credentialled Eating Disorder Clinician

Zoe Martin dietitian

First, lets start by explaining what carbohydrates are

Carbohydrates are one of the three macronutrients that are broken down to provide the body with energy, along with protein and fat.

When we eat carbohydrates they start as large complex molecules which are broken down in the gastrointestinal system into singular glucose, fructose and galactose molecules. These singular molecules are absorbed through the gut wall into the blood stream and distributed to the cells to be utilised for energy or stored in the muscles and liver as glycogen to use when needed.

There are two main types of carbohydrates found in food, simple and complex. The only difference is how quickly they are broken down and absorbed into the blood.

Simple carbohydrates are low in fibre, so the gastrointestinal system doesn’t have to do much work to break them down. They are digested and absorbed into the bloodstream in approximately 15 to 30 minutes. This makes them the perfect fuel source for training as they rapidly provide energy to the muscle and won't cause digestive discomfort during exercise. Some examples include lollies, juice, crumpets, cordial, honey, watermelon and rice cakes.

Complex carbohydrates are high in fibre and micronutrients, so the gastrointestinal system, has to do more work to break them down. They are digested and absorbed slowly into the blood, providing a controlled release of energy and feeling of fullness over several hours. Legumes, some fruits, vegetables, wholegrains and dairy are all rich sources of complex carbohydrates. We should aim to have complex carbohydrates in every meal and snack away from training for general health.

Carbohydrates are the body's preferred source of energy and should make up 45-65% of our diet, depending on how active we are. Without sufficient amounts each day our organs and muscles cannot function effectively, leading to fatigue, muscle loss, poor performance, brain fog, weakness, dizziness, digestive issues, dehydration and low mood. Here’s how.

Six reasons to love carbohydrates instead of fearing them

One: they provide energy to the brain

Glucose is the brain’s preferred energy source, however, our brains can’t store it the same way the muscles and liver can. This means we need to regularly consume carbohydrates throughout the day to supply glucose to the brain.

Without this regular supply, the brain must rely on a less efficient fuel source and doesn’t function as effectively. This leads to poor concentration, emotional regulation, decision making, critical thinking & planning - AKA brain fog.

Two: they are our muscles fuel

Carbohydrates are broken down into energy at a much faster rate and with less oxygen than protein and fat. The rapid production of energy and reduced demand for oxygen lowers your breathing and heart rates, allowing you to work harder for longer with a reduced rate of perceived exertion. Essentially, you can reach a higher intensity with seemingly less effort. This makes it the most effective and efficient fuel source for exercise.

They can also be utilised to make energy without oxygen, unlike protein and fat. This allows you to work anaerobically above your lactate threshold, in your 80% to 100% maximum heart rate zone. This zone is where a majority of adaptations are triggered, allowing you to become progressively fitter and stronger over time.

Without sufficient carbohydrates, the body must use fat during exercise, significantly reducing the intensity achieved. And no this doesn't automatically lead to more fat loss. In fact, you're likely burning less energy in your sessions, reducing your energy budget, making it harder to stay in a calorie deficit.

Three: the protein-sparring effect

Without sufficient carbohydrates, the body will use other energy sources to make glucose throughout the day. It will tap into our protein stores (the muscles) to create glucose through a process called gluconeogenesis. This causes muscle breakdown to increase, in order to generate a sufficient glucose supply, leading to a potential loss in muscle mass over time.

Consuming adequate carbohydrates ensures that the protein you eat is used for muscle building instead of glucose production.

Four: they optimise gut health

Carbohydrate foods are the only food source of fibre. Fibre is the part in plants (fruits, vegetables, legumes, whole grains) that the body cannot break down and absorb. Instead, it forms our stools, producing regular and healthy bowel motions. Fibre also feeds our good gut bacteria, which have important roles in our immune system and mental health, as well as the prevention of bowel cancer.

Five: they support hydration

For every gram of carbohydrate stored in the body, 2-3 grams of water is stored with it. Eating adequate carbohydrates helps the body hold more water, preventing dehydration. They also help aid rapid rehydration and recovery between training sessions or competitions less than 12 hours apart.

This is why you see a large amount of weight lost in the initial stage of a low carb diet. As the body depletes its carbohydrate stores it also loses the water held with it.

Six: they aid serotonin production

Carbohydrates help the brain release serotonin, an important neurotransmitter that improves mood and regulates our sleep and appetite cycles. Without sufficient serotonin production we can experience low mood, poor sleep, fatigue and over eating.

In summary, carbohydrates are essential for hydration, performance, cognitive function, muscle gains, digestion, chronic disease prevention, appetite regulation and happiness. If this has convinced you to increase your intake of carbohydrates, and you’re wondering what that might look like for you, I’m available for 1:1 nutrition consults where I provide tailored, evidence-based strategies, coaching and education.

If you need more convincing, I’d also invite you to work with me. Build a Fighter challenge participants can receive $25 off initial consults booked between the 11th of September and 16th December. Feel free to contact me via email or check out my website

and Instagram @zoemartinapd for more details.

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