How Many Kilojoules Per Day?

It’s important to determine the ideal daily kilojoule intake you should stick to to lose (or gain) weight before you start following a kilojoule-controlled eating plan to achieve your targets you’ve set for yourself.

How many kilojoules you should eat per day to lose weight

Typically, the average adult needs approximately 8 700 kilojoules per day – however this number can change depending on a variety of factors, such as:

  • Height and weight
  • Age
  • Gender
  • The amount of muscle and fat in your body
  • Your personal health status
  • Whether or not you are pregnant or breastfeeding

Kilojoules are needed in order to provide your body with energy – the energy to perform basic bodily functions such as growth and development, as well as activities such as walking, running, climbing, working and even sleeping and watching television. So it stands to reason that the more activity you engage in, the more kilojoules you will need to consume every day, and vice versa.

While it is always best to consult a doctor, dietician or health professional in order to determine your optimum daily kilojoule allowance, the following guide is suggested as a rule of thumb:

Inactive lifestyle (no exercise; sedentary job)
68kg female – 8 100kj; 80kg man – 9 600kj

Moderately active lifestyle (up to 3 sessions of moderate activity per week)
68kg female – 8 850kj; 80kg man – 10 400kj

Active lifestyle (more than 3 sessions of moderate to intense physical activity per week)
68kg female – 9 500kj; 80kg man – 11 200kj

Consuming more kilojoules than your body needs to function will result in the excess kilojoules being stored as fat – which is how one puts on weight. The good news is that the more active you are, the faster you will burn kilojoules (which is why your daily kilojoule allowance increases the more exercise you do).

In fact, recent studies have shown that doing just 2.5 minutes of high intensity exercise per day (such as 5 30-second sprints with a 4-minute rest period in between each) will help you burn up to 840 kilojoules extra a day! All of which goes to show that exercise, even light to moderate exercise, is an integral part of any health and wellness programme.

Kilojoules in food

Once you have determined the daily kilojoule allowance you will need in order to reach your health goals, such as losing weight or maintaining your current weight, you will need to take into account the kilojoule content of all the food and drink you consume, in order to put together a healthy eating plan.

The amount of kilojoules found in food depends on the actual food itself, the way it is prepared, and the size of the portion consumed at a sitting. Generally speaking, fats and alcohol are high in kilojoules, protein and carbohydrates are moderate in kilojoules, and dietary fibre is low in kilojoules, as shown here:

  • 1g fat (butter, margarine, olives, oils, nuts, avocado, coconut milk) = 37kj
  • 1g alcohol (beer, wine, cider, spirits, cocktails, liqueurs) = 29kj
  • 1g protein (meat, fish, seafood, cheese, eggs, tofu) = 17kj
  •  1g carbohydrate (starch, dairy, fruit, cereals, legumes, starchy vegetables) = 17kj
  • 1g fibre (fruit, vegetables, nuts, seeds, pulses) = 8kj

Getting the balance of kilojoules right is of great importance – not only do you want to stay within your daily kilojoule intake, you also want to ensure that you make healthy choices within each food group so as to extract all the nutritional benefits you can from each meal.

While it is possible to stay within your daily kilojoule allowance with poor nutritional choices, doing so will result in a loss of energy, as well tiredness, lethargy, inconsistent blood sugar levels, and in the long-term, illnesses such as high cholesterol and blood pressure, type-2 diabetes, obesity and heart disease. Thus, it is imperative that you know which are the best choices to make within each food group, in order to consume the right amount of kilojoules and the most nutritious foods at the same time.

Looking for more information on healthy, low-kilojoule foods? Take a look at our kilojoule-friendly food guide.