• Alex Bovell

Nutrition 411: Macronutrients

Updated: Feb 10, 2019

There are many different diets around these days claiming to be the BEST way to eat. However, most of these lack real scientific evidence. I’m studying nutrition and I’m often left scratching my head, so I can’t imagine what it’s like for those not studying it. If you’re ready to take control of your health the information can be overloading and confusing. It’s important to understand nutrition in order to set yourself up for success and avoid throwing yourself into the latest eating fad. So, I thought I’d do my best at summarising basic core nutritional information.

Nutrition is all about ensuring you give your body the macronutrients and micronutrients it requires to function optimally. Macronutrients such as carbohydrates, fat and protein are required in large amounts and will be what I summarise below. Macronutrients are defined as the structural and energy-giving caloric components of our food, they keep us energetic, strong, and alive! Just consider the fact the cells of your body are continually being regenerated and therefore what you eat today will become your body tomorrow.



Carbohydrates are the bodies quickest and preferred energy/fuel source which we need to live, grow and thrive. When exercising our body requires glucose and glycogen (stored glucose) to fuel our activity. Therefore, carbohydrates need to be readily available.


1. Simple Carbohydrates

Simple carbohydrates (monosaccharides + disaccharides) are called simple sugars because they enter the bloodstream quickly increasing blood sugar levels. Do you ever notice when you eat junk food, you have that energy buzz but you soon crash, often at the 4 pm afternoon slump? This is because your blood sugar levels are spiking and crashing, causing you to reach for more sugar!

If we consume more glucose than we require, our body stores some glucose as glycogen for later energy use. However, once we can’t store any more glycogen, our body converts glucose to triglycerides (fat) in the liver and transports it to fat cells. Simple sugars are found in many processed and refined food products such as lollies, cakes, biscuits, white bread, juices and soft drinks. They’re refined because they’ve undergone processing which strips them of fibre, vitamins, minerals and antioxidants. As a result, our body’s provided with the same amount of calories yet very little nutrients. Although fruit is technically a simple sugar it’s unrefined and provides an abundance of fibre, vitamins and minerals.

Monosaccharides are simple carbohydrates such as glucose & fructose that cannot be further broken down. These small molecules are absorbed quickly in the body, providing the fastest source of energy that increases the level of blood sugar.

Disaccharides are formed when 2 monosaccharides join together. These include sucrose (table sugar), lactose and maltose.

2. Complex Carbohydrates

Complex carbohydrates are larger molecules and must first be broken down into simple carbs before they can be absorbed. Therefore it takes our bodies longer to digest them compared to simple sugars and glucose is released slowly, providing a sustained energy supply. Additionally, because they’re digested slower, it’s less likely they’ll be converted to fat. Complex carbohydrates are found in foods such as rolled oats, brown rice, sweet potatoes, quinoa, rye sourdough and vegetables.

Oligosaccharides contain around 3-10 monosaccharide units.

Polysaccharides contain more than 10 monosaccharides joined together such as amylose & amylopectin.

3. Dietary Fibre

Dietary fibre is the indigestible parts of plant foods, found in every carbohydrate that helps keep our digestive system healthy. Dietary fibre’s important for digestive health (cleaning out our intestines and removing toxins), regular bowel movements and appetite control.

Soluble Fibre dissolves and swells in water and turns to gel during digestion, slowing down the emptying process in our stomach. Think about when you add water to oats. This helps keep us fuller for longer and encourages the growth of beneficial bacteria in our gut. Sources of soluble fibre include oats, legumes, fruits, vegetables and barley.

Insoluble Fibre doesn’t absorb or dissolve in water, like if you were to add celery to water. This dietary fibre adds bulk to stools supporting regular bowel movements. You get insoluble fibre especially from the stalks, skins and seeds of fruit and vegetables, so always eat those outside parts!


Carbohydrates get such a bad wrap because we place them all in the same box, which shouldn’t be the case. Complex carbohydrates are AMAZINGfor our body and essential to our everyday diet. Around 45-65% of our total daily food intake should come from healthy carbohydrates. Choose real food; unpackaged, unprocessed, wholefood sources such as fruits, vegetables, brown rice, quinoa, oatmeal, beans and lentils. Avoid refined sources such as table sugar, syrups, lollies, chocolate, biscuits, juices and soft drinks.


Proteins are complex molecules made up of amino acids, which are the building blocks of our body. There are 20 amino acids, 11 non-essential and 9 essential, which means we must consume these 9 essential amino acids in our diet. They include tryptophan, phenylalanine, leucine (BCAA), lysine, threonine, histidine, methionine, valine (BCAA) and isoleucine (BCAA).


Tissue structure: Protein is the main building block used during the repair and cellular growth of organs, muscle, hair, skin, nails and bones. We need protein to nourish, maintain and replace our tissues to function and grow.Hormone production: Hormones are chemicals created in one part of the body that carries messages/control other areas of the body. Hormones such as Human Growth Hormone or Insulin are produced using amino acids, making them protein hormones.Immunity: Our immune system is made up of proteins. For example, immunoglobulins (antibodies) are proteins that circulate the blood, attacking viruses & bacteria and helping fight disease.Muscle growth and maintenance: When we exercise we injure muscle fibres which is why you feel sore after training. Our body recognises muscle fibres have been torn and attempts to heal them naturally with protein. Protein enters the cells and allows repair. Protein is essential to ensure damage caused during exercise (muscle breakdown) will be repaired and rebuilt. Protein is made of amino acids, and amino acids are the building blocks of our body. We need protein to build, repair and maintain muscle tissues.Hunger: Protein takes longer to break down and digest, making it the most satiating macronutrient. Leptin is a protein made in our fat cells which signals our brain we’ve had enough to eat, switching off hunger signals.Structural Functions: protein provides shape and structure to our cells, maintaining cell membrane integrity protecting them from their surrounding environment.

Side Note: Protein isn’t a desirable source of energy. If we’re not consuming enough calories from other nutrients, protein is used for energy and our body enters a catabolic state causing muscle wastage. If we consume more protein than required, our body stores it as fat.


Complete protein contains all 9 essential amino acidsIncomplete protein is missing 1 or more essential amino acids


Protein is an essential part of the human body. We should aim to eat 15-25% of our daily food intake from protein-rich sources such as lean beef, white meat poultry, seafood, eggs, beans, tofu, lentils, nuts & seeds. More specifically, our daily protein target is around 0.8g/kg body weight.



Energy: Although carbohydrates are the quickest supply of energy, we can use fat for lower intensity, longer duration exercise. Fats provide a slower supply of energy, with each gram of fat supplying our body with 9 calories. This is nearly double supplied from carbohydrates or protein.Vitamin Absorption: Vitamins A, D, E and K are fat-soluble vitamins. Therefore, to absorb, transport and use them, we require fat.Hormones: Fat is involved in the production and regulation of sex hormones including testosterone and oestrogen.Temperature + Insulation: Fat cells stored in adipose tissue insulate the body and help maintain our body temperature.Cell membrane – Similarly to protein, fats are involved in maintaining strong cells, as they’re part of our cell membrane in the form of phospholipids.Brain function: Our brains are made up of around 60% fat and so it’s really no surprise we NEED fat for our brains to function properly.Protection: Fat is a cushion that protects our vital organs (heart, kidneys and intestines) from injury.Nerve transmission: Our nervous system is the communication method of the body. Electrical signals travel around our body through nerve cells (neurons) messaging the brain. Every neuron is protected by myelin sheath that’s made of around 70% fats. This coating ensures damage doesn’t occur and messages are being relayed correctly, allowing speedy communication and movement.


MONOUNSATURATED fatty acids (MUFA) come from plant foods such as olive oil, avocado, cashews, almonds and hazelnuts. They are high in vitamin E, an antioxidant that protects cells from damage. This is a healthy fat that helps lower bad cholesterol (LDL) and increases good cholesterol (HDL).POLYUNSATURATED fatty acids (PUFA) can be found in seafood, tahini, flaxseeds, chia seeds, sunflower oil, nuts and seeds. We need to include two types of PUFA in our diet including omega-6 essential fatty acids (EFA), linoleic acid + arachidonic acid, and omega-3 EFA’s, alpha-linolenic acid, eicosapentaenoic acid + docosahexaenoic acid, because our bodies cannot make them. Like MUFA, PUFAs can assist with improving cholesterol and heart health. Omega-3 EFA’s are particularly important due to their role in lowering inflammation, cognitive performance and mood. Our western culture consumes far too much omega-6 found in many oils of processed foods, yet not enough omega-3, increasing inflammation within the body which can contribute to many illnesses and diseases.SATURATED Fats found in meat, cream, butter and cheese increase LDL (bad) cholesterol in the body and therefore raise the risk of heart disease, among other diseases/illnesses.TRANS Fats are man-made fats found in commercially prepared foods. These are highly linked to high cholesterol and heart disease. Not only does trans fat raise LDL cholesterol, it also lowers HDL (good) cholesterol.


I know it’s easy to think if you eat fat you’ll gain fat, which isn’t the case. Like carbs, there are good/bad sources. Healthy fats are essential for the body to function properly. Excess unhealthy sources such as saturated and trans fats may be deposited in blood vessels within organs where it can block blood flow and damage organs. Opt for healthy sources such as MUFA’s and PUFA’s, found in avocado, olive oil, tahini, nuts, seeds, fish, hummus and seaweed. It’s recommended we consume 20-35% of our daily intake from healthy fat sources. It’s also important to keep saturated fat intake below 10%, and trans fat below 1% of your daily intake, to reduce your risk of disease.