Could you be under-fuelling?

Chronic illness, persistent injuries, mood swings and missed periods – under-fuelling can have a significant impact on your health.

Our bodies are like machines – they need fuel to operate.

If we consume too much fuel (or calories) we run the risk of a host of health problems, from obesity to heart disease, type 2 diabetes, and some cancers.

But it turns out eating too few calories, or under-fuelling can be just as dangerous.

So, what is under-fuelling, who is most at risk, and how can we prevent it?

What is under-fuelling and who is at risk?

The average adult needs about 8700 kilojoules a day, depending on age, size, height, health and activity level, and 60-75 per cent of this is used just to keep the body functioning.

Sports dietitian Margot Rogers says under-fuelling occurs when our dietary energy cannot support our basic metabolic processes in addition to our exercise or training regime.

“Under-fuelling can be intentional, such as in an individual seeking to lose weight, or inadvertent, such as when someone increases their training load without also increasing their energy intake,” Margot says.

And while athletes and active people are most at risk, Margot says under-fuelling can affect anyone.

What happens when we under-fuel?

Margot says under-fuelling can have a negative impact on almost every system in the body.

“If you are not consuming enough energy, the body will start to ‘switch off’ metabolic processes that are not deemed essential,” she says.

“An example of this is in females where they may no longer have a regular menstrual period.”

Pip Taylor, dietitian for Pillar Performance and former professional triathlete, says risks include osteoporosis, low iron, psychiatric and mood disorders, gastrointestinal disturbances, and for men, low testosterone or reduced sex drive.

Warning signs include fatigue, frequent illness, bone stress and fractures and lack of muscle development.

“Other signs include difficulty focusing and learning, poor sleep and decision making, slow reflexes, decreased speed and power, and vitamin and mineral deficiencies,” Pip says.

How to fuel your training

“Be aware of periods where you are increasing your training and ensure you increase your energy intake appropriately,” Margot says.

“When undertaking high volumes of training, appetite cues may not be accurate, so you need to be aware of how much you should be eating and what that looks like practically.”

She advises seeking the advice of a sports dietitian if you are unsure.

Even if you’re trying to drop a few kilos, it’s important to ensure your key sessions are fuelled, says Pip.

“Being under-fuelled for training means you raise stress hormones, blunt your immune system, don’t train as well, and your body tends to want to protect body fat stores,” she says.

Pip recommends eating a higher carb snack or meal before training sessions, and follow up with a carb and protein-rich snack for recovery.

“Anything from oatmeal with fruit, to a bagel and jam, fruit and yogurt, a simple banana – with the size and composition depending on how close to training and what else has been eaten,” she says.

Evidence suggests pre-fuelling helps sustain blood sugar levels during exercise, which can improve performance.

Pip also says to stick to regular meals and snacks, and don’t skip meals – even on rest or lower intensity training days.

“They can be lightened up with a focus on nutrient-dense fruits and veggies, but an active body requires consistent fuelling,” she says.

“Find the right balance of the key macronutrients (carbohydrates, protein, fat) and eat a colourful and varied diet to help you meet your micronutrient needs too.”

Written by Dimity Barber.