Nutrition Essentials Part 1: Macronutrients & Micronutrients
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Nutrition Essentials Part 1: Macronutrients & Micronutrients

Understanding the essentials of nutrition can help give you the tools to build a lifestyle that you love. Knowing the basics of what foods to eat and how much helps you stay healthy, but it also reduces your risk of diet-related chronic disease, and improves your wellbeing [1].

Nutrition can be an intimidating topic for a newcomer, but it doesn’t have to be. By understanding the basics, you can start feeling better and achieve and maintain your results.

The basics of nutrition begins with nutrients. These can be broken down into two major classes: macronutrients and micronutrients.


Macronutrients are how your body gets its energy, which is measured in kilojoules, or calories. There are three categories of macronutrients: protein, carbohydrates, and fat. Each is required by the body in different amounts and serves a unique purpose, which is why it is important to include all three by eating a balanced diet [2].


Protein is often referred to as the building blocks of the human body. Your body needs protein to perform many essential functions, including building and repairing muscle, bones, organs, skin, hair, and nails. It also uses protein to make hormones and enzymes, which control and regulate many functions.

Protein is made up of amino acids, which are obtained from eating a variety of foods from animals and plants. Plants contain a range of amino acids, but only animal-based protein contains all the amino acids the body needs in sufficient quantities. Therefore, plants are often deficient in one or more, which means that those who do not eat animal protein must consume a wide variety of plant foods across the day to absorb sufficient amino acids [3].

Some sources of protein which can make up part of a healthy diet are [4]:

  • Lean meats – beef, lamb, veal, pork, kangaroo, and offal
  • Poultry – chicken, turkey, and duck
  • Fish and seafood – fish, prawns, crab, lobster, mussels, oysters, scallops and clams
  • Eggs
  • Dairy products – milk, yoghurt (especially Greek yoghurt), and cheese (especially cottage cheese)
  • Legumes and beans – all beans, lentils, chickpeas, split peas and tofu

Not all protein sources are equal. Higher-quality sources like meat, poultry and fish will have a larger proportion of protein that the body is able to use [5]. Therefore, you should aim to eat more higher-quality sources for better results.


Carbohydrates are broken down by the body into glucose, which is then used for energy. The body uses this energy to perform daily activities, for growth and to maintain vital functions. For example, fuelling your brain, maintaining body temperature, keeping the heart beating and digesting food [7]. They are also a good source of nutrients [6]. Some forms of carbohydrates include rice, pasta, quinoa, potatoes, pumpkin, corn, cereal and bread.

Most carbohydrate-rich foods have benefits beyond just being an energy source. For example, some are high in dietary fibre, which will help you feel fuller for longer and in the right amount, will help to keep your digestive system healthy [8]. Low GI carbohydrates will also break down more slowly, which means energy is provided over a longer period. However, using only the glycaemic index when making choices about carbohydrate-rich foods, can be misleading. Foods with a high GI are not necessarily unhealthy and may also be a good choice for those who suffer from gastrointestinal distress.

Some sources of carbohydrates which digest well for most people and are a good energy source are:

  • Fruit
  • Rice
  • Pasta
  • Potatoes and most other vegetables

There is a lot of confusion about carbohydrates, with many fad diets pushing to cut them out to lose weight. Although you can function without them, carbohydrates are the preferred energy source of the body. Therefore, the body operates much better with carbohydrates and it is recommended they are included in most people’s diet. Individuals with higher activity levels should include a higher carbohydrate intake in their diet.


Fat is important for good health and when consumed in the right amount, is a great tool for improving body composition [9]. Fat is an energy source and also plays an essential role in the body. It stores energy, protects vital organs, assists cognitive function, and is also crucial for hormone production and balance. Fat acts as a messenger, assisting protein to do its job and helping the body absorb and store vitamins A, D, E and K [10]. Just like carbohydrates, it’s important fat is consumed in the right amounts. This is because it is energy-dense, meaning too much of it will lead to weight gain.

Fat comes in the categories of saturated, unsaturated and trans fats. Many processed foods have trans fats, including vegetable oil, margarine, cakes, biscuits, frozen pizza, cookies, and fast food. Over-consumption of trans fats can have a negative impact on cholesterol levels, and it is therefore advisable to limit your intake by eating a diet of mainly whole foods [11].

Sources of fat which can be beneficial in the right quantities are:

  • Salmon
  • Sardines
  • Nuts such as brazil nuts, almonds, and walnuts
  • Olive oil
  • Coconut oil
  • Avocado
  • Pepitas


Micronutrients refer to individual vitamins and minerals, which play a role in many important functions. There are four categories of micronutrients, and that is water-soluble vitamins, fat-soluble vitamins, microminerals, and trace minerals. They help to produce energy, prevent cell damage, strengthen the immune system, fight inflammation, healing, feeding oxygen to muscles, but also to support nervous system function. Although they are crucial for good health, your body needs them in much smaller amounts.

It can be overwhelming to try and break your daily meals into quantities of micronutrients. But there’s an alternative. A great way to get a varied intake is to eat a balanced diet, with plenty of fruits, vegetables, lean sources of protein, and healthy fats. For example, a common approach is to “eat a rainbow”. This means including a variety of foods in your diet, and adding more colourful foods in red, green, orange, and yellow to almost every daily meal [12].

At Plexus, we provide targeted training and nutrition advice. Book in a consultation to find out how we can help you build healthy habits to achieve your goals, in and out of the gym.

Read part two of our Nutrition Essentials series

Nutrition Essentials Pt 2: How to Lose Fat and Build Muscle