What are macronutrients?
Macronutrients are nutrients that are required by the body in large amounts.
Macronutrients are the building blocks for many other components needed by the body for good health.
Each macronutrient also contributes to dietary energy intake.
There are three essential macronutrients; carbohydrates, protein, and fat.
Alcohol is the fourth macronutrient.
It is not actually needed by the body, but can contribute large amounts of energy to a person’s daily intake.
Three essential macronutrients
Macronutrients are nutrients that are required in large amounts by the body. Each macronutrient contributes to dietary energy intake. There are three essential macronutrients: carbohydrates, protein, and fat. Alcohol is the fourth macronutrient. It is not needed by the body and can contribute large amounts of energy to a person’s daily intake.
Micronutrients are required in much smaller amounts but are important for growth and development. Micronutrients are made up of vitamins and minerals. Examples of vitamins are vitamin C and vitamin D, while examples of minerals are calcium and iron. Each of the micronutrients have important roles in the body from maintaining bone structure, to carrying oxygen around the body, healing wounds and building healthy skin.
Carbohydrates have the lowest energy content at 16kJ per gram, followed by protein at 17kJ per gram, and then alcohol at 29kJ per gram. Fat has the highest energy content at 37kJ per gram. Fat is a major contributor to energy with double the energy density of carbohydrates and protein.
However, most foods are a mix of macronutrients and it is rare to eat pure carbohydrate, protein or fat. Exceptions include sugar (pure carbohydrate), egg white (pure protein), and oil (pure fat).
Pure protein: Egg white. Remove yellow yolks.
Pure carbohydrate: Sugar.
Pure fat: Oil
Carbohydrates are the body’s preferred energy source. The main role of carbohydrates is to supply the body with energy for keeping all body organs working (heart pumping, lungs breathing, brain functioning) and performing daily activities such as walking, going to work or school, chasing the kids, cleaning, gardening and cooking dinner.
Carbohydrates commonly make up the largest proportion of a person’s daily kilojoule intake. Carbohydrates can be complex molecular structures such as starches and fibre or simple such as sugars. Examples of simple sugars are glucose and fructose (e.g. in honey), sucrose (e.g. in table sugar) and lactose (e.g. in milk).
Complex carbohydrates take a little bit longer to digest and break down the food into energy.
They make you feel fuller for longer which means you feel satisfied for longer.
Simple carbohydrates, on the other hand, are digested rapidly and therefore are not as satisfying.
That is one of the reasons why we recommend choosing complex carbohydrates over simple ones.
Carbohydrate Food Sources
Bread, wheat, legumes are complex carbohydrates.
Carbohydrates are found in a wide range of basic foods that provide a lot of other important nutrients. Sources of complex carbohydrates include:
- Breads, cereals, pasta and rice, particularly wholemeal and wholegrain varieties
- Wheat, rice, barley, oats, rye and quinoa
- Legumes e.g. lentils, soy beans, baked beans, kidney beans, chickpeas
- Vegetables e.g. potatoes, sweet potatoes, corn and peas
Sources of simple carbohydrates are found in some less healthy foods such as:
Sweets, fizzy drinks, biscuits and pastries are simple carbohydrates.
- Sugar, jam and honey, lollies, chocolate, fizzy drinks
- Biscuits, crackers, pastries
Protein has an important role in the growth and repair of tissues such as skin, hair, muscles and body organs like the liver, kidneys, lungs, and the digestive tract. Proteins also have many other functions including hormones, immune responses and fighting infection, and building red blood cells.
Despite the essential role that proteins play, the proportion of a person’s total intake that comes from protein is actually the smallest compared to the other macronutrients.
Protein food sources
Amino acids are the building blocks of protein. Some amino acids can be made in the body so are called non-essential amino acids. Other amino acids need to be eaten in the diet so these are called essential amino acids. Some foods provide all of the essential amino acids and these foods are called complete proteins (the examples below marked with ‘*’ are complete proteins).
Good sources of protein include:
- Meat, poultry, seafood*
- Dairy products: milk, yoghurt, cheese*
- Nuts and seeds
- Legumes (dried beans, lentils, chickpeas)
- Soy products: tofu, tempeh, milk
Fat has a very important role in the body. Fat helps transport the fat soluble vitamins A, D, E and K around the body.
These essential fatty acids are needed for brain and nerve function. Foods contain a mix of fatty acid types but they tend to be classified by the major fat type present in the food.
Fat is needed in the membranes of all body cells and is used to make some hormones and to maintain healthy skin. Some types of fat are called ‘essential’ because the body cannot make them. The consensus from leading heart and health organisations is to reduce the amount of saturated fat eaten.
Sources of saturated fat should be replaced with monounsaturated and polyunsaturated fats.
Fat food sources
There are many sources and types of fat in foods. Fats called monounsaturated and polyunsaturated fats are better for your health and these are found in:
- Oils: Olive, canola, peanut
- Nuts: Almonds, peanuts, brazil nuts, cashews, macadamia
- Oily fish: Salmon, tuna, trout and herring
- Nuts: Walnuts
- Oils/Seeds: Sunflower, sesame, flax, and pumpkin
Sources of saturated fat include:
- Full-fat dairy foods: butter, ghee, cream, ice-cream, full-fat milk and cheese
- Processed meats: Salami, bacon, ham and luncheon meat
- Chicken skin
- Fatty cuts of beef, pork and lamb.
- Plant based sources: coconut milk/oil/cream, palm oil
- Processed foods: pastries, cakes, biscuits
- Takeaway foods: hot chips, chicken nuggets, spring rolls
As already mentioned, alcohol is considered a macronutrient because if consumed, it contributes 27kJ per gram to a person’s intake. However, it is not an essential nutrient for the body.
One standard drink of alcohol in Australia provides 270kJ. One standard drink (10g of alcohol) is equal to:
- 100ml wine (12% alc. vol)
- 425ml of light beer (2.7% alc. vol)
- 375ml of mid-strength (3.5% alc. vol)
- 285ml full-strength (4.8% alc. vol)
- 30ml spirits (40% alc. vol)
More kilojoules are provided if portions are larger. Although health organisations allow a maximum of 2 standards drinks in one day, consuming alcohol during weight loss attempts can make it more difficult to lose weight because of the energy it provides.
Besides contributing energy, how alcohol is processed may also affect weight loss. Alcohol is not stored in the body so the body needs to process it and remove it as quickly as possible. After drinking alcohol, the breakdown of stored fat is reduced, therefore drinking alcohol may hamper loss of fat mass.