The 4 Macronutrients: Definition, Classification and Functions

Our bodies require a variety of nutrients for proper functioning, growth, and development. These nutrients can be divided into two main categories: macronutrients and micronutrients (5).

In this blog post, we willfocus on macronutrients, which play a vital role in providing energy, and can be considered building blocks for the body.

Macronutrients refer to the three main nutrients that our bodies require in large quantities: carbohydrates, proteins, and fats, otherwise known as lipids (5).

A fourth macronutrient, water, is also essential for our bodies (24), but it does notprovide energy and so is not often included in thisclassification.

Macronutrients  are needed in relatively large amounts, whereas micronutrients, such as vitamins and minerals,are required in smaller quantities (5).

Macronutrients are given more attention due to their significant role in providing energy, aka calories (5). If you’ve tried weight loss or muscle gain plans, you may have come across the idea of “tracking your macros”, which refers to tracking the intake of these three nutrients, carbohydrates, proteins, and fats.

The functions of macronutrients extend beyond providing energy for the body and each macronutrient has a separate and essential function. Let’s take a closer look at each macronutrient and the specific role it plays in the body.

Read more: 3 Macronutrients: What You Need To Know About Macros And How To Count Them

What Are the 4 Macronutrients?

The four macronutrients are:

1. Carbohydrates
2. Proteins
3. Fats (otherwise known as Lipids)
4. Water (although not technically a nutrient, water is essential for our bodies as it is needed in large amounts, but unlike the other macronutrients, it does not contain carbon or yield energy)

Carbohydrates

Carbohydrates are the primary source of energy for our bodies. They are found in foods such as bread, pasta, rice, fruits, and vegetables (17).

When broken down, carbohydrates are converted into glucose which is then used by our cells for energy. Any excess glucose is stored in the liver and muscles as glycogen for later use. In addition to energy, carbohydrates also play a role in the following (17):

• Regulating protein and fat metabolism – without enough carbohydrates, our bodies will break down protein and fat for energy, which may lead  to muscle loss and weight gain.
• Providing fiber – found in plant-based sources of carbohydrates, fiber helps regulate digestion and promotes feelings of satiety.Fiber is also essential for gut health as it promotes regular bowel movements (10). Research has also found that countries in which people consume high quantities of fiber in their diets, have lower colon cancer. 
• Supporting brain function and mood stability – glucose is the brain’s main source of fuel (21), and low-carb diets have been linked to changes in mood and cognitive function (14). There is also nascent research that is showing a potential connection between fiber consumption and neurodegenerative diseases through the gut-brain connections. 

Carbs are a misunderstood macronutrient, as some have linked some types of carbohydrate- consumption with weight gain and blood sugar spikes. Simple carbohydrates that are also described as “low-quality” carbs by researchers, are the ones that most healthcare providers discourage people from consuming (20) (22). However, it’s important to remember that not all carbohydrates are created equal and that carbohydrate consumption is also essential for survival and optimal health, as well as that elimination diets may lead to weight loss but they may also deprive the body of essential nutrients (19). 

Simple carbs such as refined sugars and white bread, can provide quick energy but may lack essential nutrients. On the other hand, complex carbs that are found in whole grains, fruits, and vegetables may offer a steady release of energy and vital nutrients. This steady release may be due to the low glycemic index of these types of foods, including but not limited to: Bran cereal, apples, oranges, kidney beans, black beans, lentils, wheat tortilla, skim milk, cashews, peanuts, carrots(6). 

At this point, it is important to mention hyper processed foods that may advertise themselves as containing complex carbs, but that may also be containing a lot of “hidden” emulsifiers, flavor enhancers, and preservatives that may be contra-indicated for optimal health. For this reason, when purchasing pre-made foods and snacks, it is important to read the labels. A good rule of thumb is, if you couldn’t buy the ingredients that the food is made of at the supermarket, then it may be best to avoid the food or snack altogether and buy something made of simpler ingredients.  

We compiled a list of Carb-Friendly Juices for Weight Loss that may support your weight loss journey. Again, in considering these options, it is important to go through ingredients’ lists and make sure they aren’t hyper-processed, for optimal options. 

Proteins

Proteins are often referred to as the “building blocks of life”, due to their role in building and repairing tissues. They can be found in foods such as meat, fish, poultry, dairy products, beans, and legumes (15).

Our bodies need protein for various functions such as:

• Creating enzymes and hormones – proteins play a vital role in the production of enzymes that help with digestion and hormones that regulate various bodily processes, such as muscle contraction, among others (18).
• Supporting immune function – antibodies and cytokines, which can help fight infections and diseases, are made up of proteins. According to the cited article, “ Adequate dietary provision of all amino acids is necessary for sustaining normal immunocompetence and protecting the host from a variety of diseases in all species” (2).
• Repairing and maintaining muscle tissue – proteins provide the essential amino acids that are needed for muscle growth and repair after physical activity (7).

When we consume protein, it is broken down into amino acids that are then used by our bodies to build and repair tissues. Unlike carbohydrates and fats, our bodies don’t store excess protein for later use (9). 

Protein also plays a role in weight loss and maintenance as it is the most satiating macronutrient and has a higher diet-induced thermogenesis compared to fat and carbs. Therefore, it’s important to consume enough protein throughout the day to meet your body’s needs. Protein consumption may also play a crucial role in promoting weight loss in humans (23).

When calculating macros, the recommended daily intake of protein is generally around 0.8-1 gram per kilogram of body weight. This means that a 60 kg person, would need to consume 48-60 grams of protein per day to meet this recommendation. However, this may vary depending on individual factors such as activity level and health goals, that may require people to consume higher levels of protein (9).

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Fats

Fats are another, often misunderstood macronutrient, as they contain more calories per gram than carbohydrates or proteins. While their caloric density is higher per gram, than that of carbohydrates or proteins, fats are essential for multiple bodily functions and can promote health.  Sources of fat are also important, while fat deriving from avocados, for example, is not the same as fat deriving from fast food burgers. 

Fats serve various, essential functions in the body, including, but not limited to (8) (12):

• Providing energy and storing vitamins – fats are a concentrated source of energy and help absorb fat-soluble vitamins such as A, D, E, and K, that are essential for health.
• Maintaining healthy cells – fats are essential for maintaining cell membrane structure, and for supporting their function.
• Providing insulation and protection for vital organs – fats help cushion and insulate our organs, protecting them from outside forces.
• Regulating hormone production – certain hormones such as estrogen and testosterone are produced from cholesterol, a type of fat, which means that hormones can play a role in hormone production, with various effects on peoples’ bodily functions (4).

In addition to these roles, fats can also help slow the absorption of food, which may keep us feeling full for longer periods, and may help with weight management (11). The key to making healthier choices, is choosing healthy sources of fat such as avocados, nuts, and olive oil, and fatty fish such as salmon. Here, it is important to mention that larger fish, such as salmon or tuna, may contain higher levels of mercury absorbed by the fish in open waters, and for that reason the consumption of smaller-sized fish, such as sardines, is even more preferable, to avoid heavy metal consumption (3). 

The connection between high-fat consumption and heart disease has been documented in research, however the type of fats consumed, is important in this conversation. Saturated and trans fats, which can be found in fried foods and processed snacks, are considered unhealthy and should be limited in large amounts. On the other hand, unsaturated fats, which can be found in plant-based sources such as avocados and olive oil, can have protective effects on one’s heart health (1).

In our Eating Too Much Healthy Food article, we discuss how even nutritious foods can lead to weight gain if they’re consumed in excess.

Water

Water may not be a macronutrient, but it is essential for our bodies to function properly. Our bodies are made up of approximately 60% water, and every system in our bodiesrelies on it.

Water helps with the following (13):

• Regulating body temperature – when we sweat, water evaporates from our skin, which cools us down.
• Removing waste – water helps flush out toxins and waste products through urine and sweat.
• Lubricating joints – the synovial fluid that cushions our joints is made up,mostly, of water.
• Transporting nutrients and oxygen to cells – blood, which carries these vital elements, is also, mostly made up of water.

The recommended daily intake of water varies for each individual depending on factors such as:

• Their activity levels – those who exercise regularly will need more water to replace what is lost through sweat.
• Their environment – hot and humid weather can increase the amount of water that is lost through perspiration (sweating).
• Health status – certain health conditions may require an increase in fluid intake. For more information, please consult with your health care provider.

A good rule of thumb is to aim for 8 glasses of water a day, but listen to your body and drink more if you feel thirsty. Other sources of water, such as fruits and vegetables, also contribute to our daily intake, which means that a diet that is rich in watermelons, cucumbers, tomatoes, and other fruits and vegetables that contain water, may also be helpful to increasing our daily water intake

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FAQs

• What is the difference between macronutrients and micronutrients?

The difference between macronutrients and micronutrients lies in their respective functions, and in the amounts needed by one’s body. 

Macronutrients, such as carbohydrates, proteins, and fats, make up the bulk of our daily caloric intake and provide energy for bodily functions. On the other hand, micronutrients such as vitamins and minerals are required in smaller amounts, and play essential roles in maintaining overall health and preventing deficiencies (16).

• Do I need to track my macronutrient intake?

Tracking macronutrients can be beneficial for those who are looking to reach specific health or fitness goals. However, this is not required for making healthier choices, as setting an intention of consuming a variety of macronutrients, deriving from natural sources, and that are not overly-processed, would be just as effective. Also, continuous tracking of macronutrients should be avoided if one tends to exhibit problematic eating behaviors, or to overly- control their food intake, to prevent this from aggravating potentially pre-existing eating disorders. 

Along these lines, for people who find tracking macronutrients beneficial,  tracking can ensure they are consuming enough of each macronutrient, and can make adjustments as needed. However, it is essential to listen to your body’s hunger signals and not become too restrictive or obsessive with tracking.If you find yourself developing such behaviors, please contact a mental health provider for additional support.

• What are the 4 basic steps to determine your macros?

If you find that tracking macronutrients may be beneficial to you, here are four steps you may follow, to determine what quantities of each macronutrient your body may need: 

1. Calculate your total daily energy expenditure (TDEE) – this is the number of calories you burn in a day through physical activity and bodily functions.
2. Set a calorie goal based on your health and fitness goals. Please follow guidelines of goals that are healthy and not excessive, to avoid overexertion or excessive restriction. 
3. Determine your protein intake – multiply your weight in kilograms by 0.8-1 to get your recommended protein intake in grams (e.g. a 60kg individual will need to consume 48 to 60 grams of protein per day).
4. Fill in the remaining calories with carbohydrates and fats – the ratio of these two macronutrients can vary depending on personal preference and goals.

Once you’ve calculated your macros, it may be beneficial to regularly re-evaluate and adjust as needed based on changes in activity level or health goals.

For example, if you increase your physical activity, you may need to increase your carbohydrate intake to fuel your workouts. If you’re looking to lose weight, reducing your overall calorie intake may be necessary. For more information and a personalized diet and exercise plan, please contact your healthcare provider.

• What is the rule of macros?

The rule of macros, also known as the 80/20 rule, suggests that 80% of your daily caloric intake should come from whole, nutritious foods while allowing for 20% flexibility for treats or less healthy options. This rule promotes balance and moderation in food choices and can help prevent feelings of deprivation or restriction.

This rule can be helpful in finding balance because:

• It encourages a healthy and sustainable approach to eating.
• It focuses on the overall quality of food rather than restricting certain macronutrients.
• It allows for flexibility, which makes it easier to stick with in the long term. 
• It promotes a positive relationship with food and avoids strict rules or labels.
• It can help prevent nutrient deficiencies by including a variety of whole foods in your diet. 

Check out our Macros Food List for ideas on nutritious, macro-friendly foods to incorporate into your diet.

The Bottom Line

Carbohydrates, proteins, fats, and water are all essential macronutrients our bodies need to function properly. Each of them plays a unique role in maintaining our overall health and well-being. 

Carbohydrates provide a quick source of energy, proteins help build and repair tissues, fats have various functions in the body, and water is essential for all bodily processes. Remember to choose whole food sources for these macronutrients and consider your body’s individual needs when it comes to intake.