What is a Macronutrient?

Macronutrients are proteins, fats and carbohydrates. These are the chemical compounds that we consume in the largest amounts to provide energy and support growth. A complete diet should consist of these macronutrients, in varying amounts specific to the individual. Dietary fibre and water also constitute macronutrients and maintain optimal human health. 

Human populations have lived on diets that vary greatly from one another around the world. The percentages of these macronutrients differ depending on the region and food availability. An example of these differences can be clearly seen in a traditional Alaskan Inuit diet versus a typical British diet. 

Inuit diets are high in fat with moderate protein and carbs (41% fat, 33% protein and 26% carbohydrates). Whereas historical British diets are very high in carbs and low in protein and fat (87% carbohydrates, 12% protein, 1% fat). 

Let’s break down each category of macronutrient, and answer the question - What are carbohydrates, fats and protein?

Carbohydrates - macronutrients


Carbohydrates are sugar compounds and can be small or large according to their number of sugar units. Starting with simple sugars and moving to complex carbohydrates, we have monosaccharides, disaccharides, oligosaccharides and polysaccharides. Here they are in the table below.

















Carbohydrates are grouped chains of starch, cellulose or sugars that are easily broken down into glucose for the body to use as energy. 

Carbohydrates are a primary source of energy for brain and muscle tissue. However, the body can also break down fat and protein into glucose to use as energy. Because these other macronutrients are filled with micronutrients, such as minerals, antioxidants and vitamins, they ‘pack more punch’ per gram and serve a greater purpose for the body’s overall metabolic needs.

High-Carbohydrate Health Concerns

A high carbohydrate diet, especially if consumed in its simplest forms, provides the body with bountiful energy. However it is often utilized just as quickly as it is consumed, which can cause an energy deficit. This is felt in the body as a blood-sugar dip and is followed by an energy slump. 

The body sends signals to the brain demanding more carbohydrates for more energy. This can trigger a cycle of craving sugar or carbohydrate-rich foods, which ultimately fail to provide the body with appropriate energy for any length of time. 

The key to avoiding this metabolic problem is consuming a diet focused mostly of protein and fat sources, supplemented with carbohydrates as needed. 

The following are examples of carbohydrates that typically cause a spike and subsequent drop in blood- glucose. If they are to be consumed, it should be mindfully and minimally. Not as a primary food source in the diet.

High & Refined Carbohydrates

  • Sugar
  • Grains – bread, flour, pasta, rye, rice, quinoa, corn, noodles, polenta, oats
  • Starchy vegetables – parsnips, white potato, turnips
  • Refined carbohydrates – biscuits, packaged foods, sweets, crackers
  • Fruit juice
  • Alcohol

So what are the best carbohydrates?

It may not be well known that fruits and vegetables are also considered carbohydrates. They are a far better choice as well, because they behave differently in the body compared to the simple carbohydrates as mentioned above. Fruits and vegetables are absorbed more slowly and as such don’t cause an energy slump. Therefore, they are a superior choice for your plate when putting a meal together.

What else is good about fruits and vegetables?

Fresh fruits and colourful vegetables in their natural form consist of fibre, vitamins, minerals and carbohydrates together. Generally, fruit has a higher sugar (carbohydrate) content than vegetables, which means the overall recommended serving per day is usually less than that of vegetables. 

This is to maintain a balanced macronutrient diet. Fruits and vegetables can be difficult to categorize into the conventional food groups, but because of their various health benefits aside from just providing energy, they can be included at each meal or as a snack to supplement a balanced diet.

In other words, including 5-7 servings of fibrous vegetables and 2-3 serves of whole fruit during the day are the standard guidelines for a healthy diet.

Fat - macronutrients


Fat obtained from the diet is required for adequate brain, hormone and reproductive function. Fat protects skin and vascular cells and helps transport vitamins to their target tissues. Fats are needed for the construction and maintenance of cell membranes, to maintain a stable body temperature and serves as an overall protective macronutrient in the body. 

The 3 types of dietary fat include:

  • Saturated Fat
  • Polyunsaturated Fat
  • Monounsaturated Fat

Food sources of these fats are in the table below.

Saturated Fat

Polyunsaturated Fat

Monounsaturated Fat

Coconut oil


Beef fat


Egg yolks


Sunflower Seeds

Sesame Seeds


Olive oil


Wild Salmon

Whole Grain wheat

Beef fat

Whole Milk




Sunflower Oil


The smallest components of fat are termed fatty acids. These can be grouped into essential and non-essential fatty acids. Non-essential fatty acids can be synthesised in the body, however essential fatty acids cannot and must be obtained through the diet. 

Essential Fatty Acids

The two fatty acids that are essential for human health are:

  • Alpha-linolenic acid (omega 3)
  • Alpha-linoleic acid (omega 6)

These fats MUST be obtained from the diet. Food sources of these essential fats include fish, seafood, flaxseeds, hemp seeds, olive oil, soy, chia seeds, sunflower and pumpkin seeds, leafy greens, nuts. 

A deficiency of healthy fat in the diet can cause a range of health issues. These include fatigue, poor sleep, poor memory and nervous system problems. 

The key is, it's all about quality animal and plant sources of fat in moderate amounts from cooking, as well as cheese, natural full fat yoghurts and butter.

These are typical sources of saturated fat, which help to promote satiety and energy. Be sure to include polyunsaturated and monounsaturated sources of fat from plants, nuts and seeds as well. Fat in its natural form is very healthy and helps transport the fat-soluble vitamins A, D, E and K. 

Hydrogenated oils, vegetable oils and trans fats are detrimental to health. These fats are found in deep fried or processed foods, such as packet crisps, margarine or food cooked in canola oil.

Below are my top sources for healthy fats:

  • Nuts & nut butters
  • Seeds
  • Avocados
  • Olive oil
  • Coconut oil
  • Butter
  • Cheese

Protein - macronutrient


Proteins are organic compounds composed of amino acids joined by peptide bonds. Many of these amino acids are non-essential and the body can synthesise them internally. However there are some key essential amino acids, crucial for human health which must be obtained from food. 

Essential Amino Acids

Non-Essential Amino Acids

















Aspartic Acid

Glutamic Acid




Protein is required for basic human survival. Protein is essential for enzyme activity, blood cell transportation, immune function, building building, mood and sleep and energy production. 

Enjoying protein-rich snacks, such as nuts, hummus and cheese throughout the day, aside from main meals, will ensure you meet your daily protein requirements.

Examples of protein include:

  • Meat – beef, lamb, pork, goat, venison, kangaroo, veal
  • Poultry – turkey, chicken
  • Fish and seafood – white fish, squid, scallops, oysters, sardines, salmon, tuna
  • Eggs – organic and free range
  • Tofu - organic
  • Nuts/seeds – cashews, walnuts, hazelnuts, almonds, pecans, brazil nuts + nut butters, tahini
  • Legumes/beans – peanuts, lentils, chickpeas, green peas, green beans, navy beans, cannellini beans
  • Fermented dairy – natural yoghurt, cheese

Everyone’s protein requirements will differ depending on age, gender, activity level and other concomitant health conditions. 

Protein is the one macronutrient that has a defined intake value that many different health experts all agree on. As a guide, an average healthy adult should be eating a minimum of 1.2g of protein per kilogram of body weight.

Macronutrients: What Does Science Say?

It’s important to get the macronutrient balance right for optimal health. Certain life stages, such as pregnancy warrant special attention to macronutrient intake. Each person will have different needs, across different life stages and growth periods. As discussed in a recent scientific paper, eating too much and not enough have health consequences. 

People who are overweight have an elevated risk of dying in middle age of degenerative diseases while the underweight are at increased risk of premature death from infectious conditions. Nutrition-related conditions worthy of special attention from caregivers include excess vitamin A, excess vitamin D, and deficiency of magnesium.

An article published in 2020 reviewed various popularised diets in relation to weight loss. The overall consensus here is that high-protein and low-carb diets as well as intermittent fasting may be a useful tool in weight loss initiation. However there can be medium and long-term side effects from adhering to restrictive diets such as these. As a result, the authors suggest proceeding with caution when following these diets. 

Another study regarding the development of a potential anti-alzheimer’s diet published in the journal Scientific reports, revealed a lower protein diet could protect against alzheimers. Maintaining this macronutrient balance, with lower amounts of protein, was deemed protective against Alzheimer’s disease onset.

Article References

Australian Government, National Health and Medical Research Council, Nutrient Reference Values for Australia and New Zealand, The Nutrients Reviewed. https://www.nrv.gov.au/nutrients, viewed 21 Dec 2021

Freire R. (2020). Scientific evidence of diets for weight loss: Different macronutrient composition, intermittent fasting, and popular diets. Nutrition (Burbank, Los Angeles County, Calif.), 69, 110549. https://doi.org/10.1016/j.nut.2019.07.001

Kim, M., Basharat, A., Santosh, R., Mehdi, S. F., Razvi, Z., Yoo, S. K., Lowell, B., Kumar, A., Brima, W., Danoff, A., Dankner, R., Bergman, M., Pavlov, V. A., Yang, H., & Roth, J. (2019). Reuniting overnutrition and undernutrition, macronutrients, and micronutrients. Diabetes/metabolism research and reviews, 35(1), e3072. https://doi.org/10.1002/dmrr.3072

Mousa, A., Naqash, A., & Lim, S. (2019). Macronutrient and Micronutrient Intake during Pregnancy: An Overview of Recent Evidence. Nutrients, 11(2), 443. https://doi.org/10.3390/nu11020443

Nassar M. F. (2019). The macronutrients' interplay. Clinical nutrition (Edinburgh, Scotland), 38(6), 2943–2944. https://doi.org/10.1016/j.clnu.2018.11.019

O'Grady, J., & Shanahan, F. (2021). Macronutrients, microbiome and precision nutrition. Current opinion in gastroenterology, 37(2), 145–151. https://doi.org/10.1097/MOG.0000000000000705

Studnicki, M., Dębski, K. J., & Stępkowski, D. (2019). Proportions of macronutrients, including specific dietary fats, in prospective anti-Alzheimer's diet. Scientific reports, 9(1), 20143. https://doi.org/10.1038/s41598-019-56687-2

Venn B. J. (2020). Macronutrients and Human Health for the 21st Century. Nutrients, 12(8), 2363. https://doi.org/10.3390/nu12082363

Wikipedia Contributors. (2021. December 22). Macronutrients. Retrieved from Wikipedia website: https://en.wikipedia.org/wiki/Nutrient#Macronutrients, viewed December 22 2021