What are Macronutrients?
Macronutrients are the nutrients that we use for energy to sustain vital functions such as breathing and heart function. They also provide fuel for everyday activities such as walking. Macronutrients are divided into carbohydrates, proteins and fats.
Carbohydrates are not essential for survival. We can make our own carbohydrates through a process called “gluconeogenesis”, which involves the conversion of protein or fat to glucose. High carbohydrate-containing foods are generally nutritionally poor and energy dense e.g. bread, rice, pasta, pastries, and sweets. Carbohydrates consist of chains of sugar molecules joined together. Simple carbohydrates (or high glycaemic index/GI foods) include monosaccharides (one sugar unit) and disaccharides (two sugar units joined together). Complex carbohydrates (or low GI foods) are polysaccharides and consist of multiple sugar units joined together. Current dietary advice recommends that we consume plenty of complex carbohydrates (whole grain breads and cereals) and minimise simple carbohydrates (lollies, juice etc). The problem with this scenario is that our bodies cannot differentiate between simple vs complex, high vs low, monosaccharides vs disaccharides vs polysaccharides. Regardless of the type of carbohydrate that is consumed, our body will simply snip carbohydrates into single units of sugar. For every gram of carbohydrate that we consume, our bodies will convert this to about 4.5 teaspoons of sugar. The average Australian diet has 200-300g of carbohydrates per day, which translates to 44-67 teaspoons of sugar. We are overwhelming our bodies with sugar every day, which is a key driving force in lifestyle-related disease.
In contrast to carbohydrates, dietary fat is essential for survival. Certain types of fat (essential fatty acids) cannot be synthesised by the body and must be obtained from dietary sources. Some functions of fat include:
Serving as a metabolic buffer zone and portable source of energy.
Fat is an essential component of cell membranes.
It is a precursor to hormones such as cortisol, testosterone, oestrogen and progesterone.
It is a precursor to vitamin D
It is used in the synthesis of bile acid and lubricates our joints.
The brain is 60% fat.
Proteins consist of amino acids, which are essential for life. To name a few functions, protein is critical in building and repairing tissue, producing enzymes and hormones, and supporting the immune system. The minimum recommended daily intake of protein is 1g/kg of lean body weight to prevent disease. However, to thrive, we need closer to 1.2-2g/kg body lean weight. In general, it is very difficult to eat a lot of energy in protein vs very easy to eat a large amount of energy in carbohydrates. As a general guide:
150g Raw beef contains 30g protein.
160g of yoghurt contains 15g of protein.
¼ cup almonds contains 7g protein.
