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Healthy ways to reach your daily energy (kj) requirements

Jemma O'Hanlon

Calculate your daily energy requirements for optimal health

A young woman smiles as she bites into half an orange
A young woman smiles as she bites into half an orange

From sharing a meal with family and friends to grabbing a bite on the go, eating is one of life’s simple pleasures. But food is, first and foremost, the fuel that keeps our bodies functioning. Just like different car engines need differing amounts and types of fuel to keep them running, our bodies have different daily energy requirements, too.

Fat, carbohydrates and protein found in food are broken down by the body to release energy (measured in kilojoules), which fuels literally everything our bodies do. That includes the metabolism of cells, hormones and enzymes as well as heart and brain function, blood circulation, breathing and physical activity. But if we’re taking in more energy than we’re using, we store the extra as fat and can start to see our weight creep up.

“When it comes to energy requirements, in order to maintain a healthy weight we need to be balancing the energy that goes in with the energy we expend, through activities like exercise,” advises Jemma O’Hanlon, accredited practising dietitian and nutritionist. “If the balance is out of whack, and we’re consuming more than we’re burning off, we can be at risk of weight gain and other health-related complications.”

What is our daily energy (kj) requirement?

To maintain a healthy weight, the average adult needs around 8700 kilojoules a day.

However, our individual requirement depends on our age, gender (men generally need more energy than women as they have more muscle tissue) and everyday activity levels as well as our weight, height, body composition and genetics. Women who are pregnant and breastfeeding also have different daily energy requirements.

A young man prepares healthy food in the kitchen

How do we calculate how many kilojoules we need on a daily basis?

Jemma recommends visiting an accredited practising dietitian for help understanding the daily energy requirements for adults and how much you need to be eating for energy. You can also get a good estimate of your daily energy requirements with an online daily energy requirement calculator such as:

The best way to figure out your daily energy requirements, says Jemma, is to slow down and really listen to those hunger cues.

“With our busy lives, it’s easy to fall into the trap of eating more highly processed junk foods, which are readily available,” she explains. “We’re also cooking less from scratch and we don’t sit down and enjoy our food mindfully as much as we used to. We tend to eat on the run or while we’re working, which means we’re less in tune with what our bodies need and our hunger signals.

“If we eat when we are genuinely hungry and stop eating when we feel comfortably satisfied, we’re going to be on a good path for meeting and not exceeding our energy needs,” she says.

What foods give us the energy we need?

As the daily energy requirements for adults vary from person to person and according to our goals, there’s no one-size-fits-all energy-input-to-energy-output ratio. The ideal situation, explains Jemma, “is that we’re fuelling our bodies with a variety of foods every day that provide enough energy to support our daily functions and allow our bodies to repair and recover when we are at rest.”

Low-carbohydrate diets have become popular for weight loss, but carbs are the only fuel source for some vital organs — including the brain, central nervous system and kidneys — and are essential to fuel our bodies.

“Carbohydrate-containing foods like fruit, wholegrains and legumes contribute energy to help fuel our brain and muscles,” says Jemma.

Carbohydrate-containing foods like fruit, wholegrains and legumes help fuel our brain and muscles

“When we eat lots of fruit, vegetables, nuts, seeds, legumes, wholegrains and protein-rich foods, we give our bodies the energy we need as well as important vitamins and minerals, which can also help support our energy levels.”

If you find yourself lost for words during an important meeting, using sugar and caffeine to keep going throughout the day or you’re just feeling ‘out of sorts’, you might benefit from a few simple lifestyle changes. Check out our article 7 tips to increase your energy levels naturally for more.

Please note: The tips throughout this article serve as broad information and should not replace any advice you have been given by your medical practitioner.

Jemma O'Hanlon

Jemma O’Hanlon is an Accredited Practising Dietitian and Nutritionist who inspires Aussies to transform fresh produce into easy, delicious meals. She believes that if we embrace food with gratitude, enjoy our meals mindfully and maintain an active lifestyle, we can be healthier and happier. When she’s not in the kitchen Jemma loves to run and enjoys chilling at the beach.