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Macronutrients are the nutrients that provide us with the bulk of the energy we need to grow and repair; we all know them as fats, carbohydrates and protein. Our bodies require a balance of all three macronutrients to function properly throughout the day. That’s right, all three. That’s why fad diets that promote ‘cutting carbs’ and ‘eliminating fats’ are really unhelpful; we simply can’t live without them. Here’s a quick low-down on how each of the macronutrients fuel our bodies:


Carbohydrates are the preferred energy source for the body. They provide fuel for your brain, tissues, cells and central nervous system. In fact, our brains won’t accept energy from any other type of fuel. Carbs also help keep our digestive system healthy by feeding the friendly bacteria that live in our intestinal tracts.

The problem with carbs is that many of us eat too much in its refined form, sugar, which has little nutritional value but packs a kilojoule punch. So when possible, choose carbohydrates that are low in sugar and high in fibre like wholegrain breads, cereals, pasta, and rice, alongside fruit, pulses and vegetables.


Protein is a key element in managing weight as it satisfies hunger and supplies the body with essential amino acids needed to build and repair muscle, bone and tissue. It also helps control hormone levels. Unlike other energy sources, protein cannot be stored in the body and is best consumed regularly to get the most benefit.

Good sources of protein include meat, eggs, seeds, nuts, soy products, beans and dairy.


Fats and oils are very important in your diet. Fat protects your organs, keeps you warm and helps your body absorb and move nutrients around. It also helps hormone production. Saturated fats (found in animal products and highly processed food) should be limited, as they have the potential to increase bad cholesterol in the blood. However, mono-unsaturated and polyunsaturated fats (mainly found in plant products) tend to lower blood cholesterol.

Good sources of fats include avocado, olive oil, cheese and nuts.

Macronutrients and energy

Every food we consume has a different balance of carbs, protein and fat. And each of these macronutrients has a different amount of energy (kilojoules) per gram.

Macronutrient Energy per gram
Carbohydate 16kj (4 cal)
Protein 17kj (4 cal)
Fat 37kj (9 cal)

In addition to the three macronutrients, there is one other food component that our body can extract energy from: alcohol. But unlike carbs, protein and fats, which play a huge role in supporting our bodies’ function and development, alcohol whacks us with a load of extra kilojoules (not to mention a hangover) while providing no real nourishment to our body.

Alcohol 29kj (7 cal)

We need to take in less energy than we expend in order to lose weight. So by knowing the kilojoule count in everything you eat and managing your energy intake with your energy output, you can create an energy deficit. Translation: eat all food groups, but choose less energy dense food, eat the right quantity of macronutrients for your body type, move more, and the weight will come off.