Macronutrients & Their Role In Your Body

Introduction to macronutrients

Macronutrients (macros) are the nutrients our body needs in large quantities, including protein, carbohydrates and fat. On the other hand, micronutrients consist of different vitamins and minerals and are also essential but consumed in smaller quantities. 

Counting and keeping track of macros can help you reach various health goals. This blog will take you through each macronutrient and its role in our bodies. The United States Department of Agriculture (USDA) has provided a rough guide as to how much of each macronutrient our body requires:

• Carbohydrates: 45-65% of your daily calories

• Protein: 10-35% of your daily calories

• Fats: 20-35% of your daily calories

However, it is important to note that these recommendations could change based on age, activity levels, gender and other factors. 

Protein

What is it?

Protein is an essential macronutrient that is highly researched, particularly in sports nutrition and exercise. It is found throughout the body in our muscles, bone, skin and hair and is made up of amino acids, often referred to as the building blocks of protein. There are 20 amino acids, of which nine are essential, meaning our bodies cannot synthesise them so we must get them from the foods in our diet.  

What does it do?

Proteins are essential for the structure, function and regulation of the body’s tissues and organs. The different functional and structural properties include:

• Growth and development throughout different life stages

• Skeletal muscle contraction, growth, recovery and adaptation from physical activity and exercise

• Building joint cartilage, hair, skin and nail cells

• Transportation of small molecules within cells and around the body

• Building other functional and cellular components, including hormones, enzymes and antibodies

How much do you need?

Your protein requirements will differ depending on your age, gender, weight, activity level and fitness goals. The Recommended Dietary Intake Report (RDI) suggests that the average sedentary adult consumes 0.8 grams of protein per kilogram of body weight daily, or between 10% and 35% of your total calorie intake daily. This, however, is the minimal requirement for our bodies to function normally, and most of us may need more than that, mainly if we are active. 

The Academy of Nutrition and Dietetics suggests that the more active you are, your body needs more protein. If we want to reap the maximum benefits of protein, we should eat more than the RDI suggests. Advice on protein requirements varies due to conflicting study results; however, recent scientific research states that the recommended daily protein intake is around 30% of our daily calories. For someone consuming 2000 calories per day, this equates to 600 calories from high-protein foods.

For more on protein requirements, read our blog: How much protein do you need per day?

Where to get it?

Protein can be found in several different meat and plant-based foods, and you are encouraged to get your protein from various sources. Some high-protein foods include:

• Eggs

• Chicken breast

• Greek yoghurt

• Lean beef

• Salmon

• Lentils

• Quinoa

• Protein Supplements such as True Protein WPI90

Carbohydrates

What is it?

Carbohydrates are a macronutrient that our bodies turn into glucose to use as energy to function. They make up the most considerable portion of one’s calorie intake as they are the most important energy source. 

What does it do?

As described above, carbohydrates provide us with energy as well as aid in the following functions:

• Fibre, which is a source of carbohydrates, aids in digestive health.

• Some carbohydrates can increase healthy gut bacteria, which is also associated with mood and mental disorders.

• Carbohydrates are essential for the production of serotonin which is a mood stabiliser

• Carbohydrates can also help to regulate blood sugar which, if drops too low, can cause difficulty concentrating, confusion and drowsiness.

How much do you need?

There is no recommended dietary intake (RDI) set in the Australian Dietary Guidelines. However, the suggested amount is between 45% and 65% of your total energy intake. If we do not consume enough carbohydrates, we may not have enough energy for physical and mental well-being. On the other hand, if we consume too much, the unused carbohydrates are converted to fat, risking an increase in body weight.  

Where to get it?

There are three types of carbohydrates, and these include:

1. Starches (also known as complex carbohydrates) - legumes, rice, wheat, grains, cereals

2. Fibre - fruit, vegetables, legumes, nuts, seeds

3. Sugars - glucose, fructose, lactose, sucrose

Some good sources of carbohydrates include:

• Oats

• Quinoa

• Bananas

• Oranges

• Sweet potato

• Apples 

• Chickpeas 

DEBUNKING THE MYTH

The idea that carbs are bad is one of the most commonly misunderstood facts about the macronutrient. The key is understanding the right carbs to eat, not avoiding them! As discussed earlier, carbohydrates are made up of fibre, starch and sugar. While fibre and starch are complex carbohydrates, sugar is a simple carb. 

Complex carbohydrates are the ones that we want to include in our diet. They are higher in fibre and take longer to digest meaning the energy they provide lasts longer and keep us feeling full. Main sources of complex carbs include fruits, vegetables, nuts, whole-wheat bread, oats and rice. 

Fats

What is it?

While fats are often misunderstood to be bad for us, dietary fat is an essential part of our diet. Like many other foods, over-consumed fats can be harmful to your health; however, when eaten in moderation can provide us with significant benefits. 

There are four types of dietary fats, each with different health benefits, risks and sources. They are:

• Saturated fats

• Trans fats

• Monounsaturated fats

• Polyunsaturated fats

What does it do?

Dietary fat has two main functions: providing your body with energy and supporting cell function. Other functions include:

• It helps keep skin and hair healthy

• Insulates the body and protects organs

• It can also help your body to absorb nutrients and produce essential hormones

How much do you need?

You should consume 20-35% of your calories from fats and less than 10% from saturated fat. If you consume too little fat, you could risk vitamin deficiencies, skin inflammation, hair loss, slow wound healing and a poor immune system. On the other hand, consuming too much fat could result in weight gain, as fats are typically higher in calories than protein and carbohydrates. 

Where to get it?

Some healthy sources of fat include:

• Avocados

• Cheese

• Eggs (including the yolk)

• Fatty fish like salmon and sardines

• Full-fat yoghurt

• Chia seeds

• Nuts

Conclusion

Macronutrients are the nutrients that we need in more significant amounts. Understanding their roles in our bodies and how much we need can help guide us to eating a diet that will benefit our lifestyle. For our bodies to function optimally, we must eat a nutritious and diverse diet consisting of carbohydrates, protein, fats and micronutrients.

Key Takeaways

• Macronutrients are the nutrients we need in large amounts: Carbohydrates, protein and fats

• We will get most of our energy from carbohydrate sources, followed by protein, then fats

• All have different roles in our bodies and come from other types of foods

• Counting macros could be an alternative to counting calories

References

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905294/

2. https://doi.org/10.1093/ajcn/59.3.682S

3. https://medlineplus.gov/dietaryfats.html

4. https://www.nhmrc.gov.au/adg

5. https://dietitiansaustralia.org.au/health-advice/protein

6. https://www.legislation.gov.au/Details/F2018C00942