Macronutrients
Carbohydrates, protein, and fat are macronutrients that provide your body with energy. This is where the calories (energy) in food come from. We need macronutrients in large amounts for energy and to maintain the body's structure and systems.
Carbohydrates
Carbohydrates are found in a variety of food and drink, and provide the body with energy. Carbohydrates break down into glucose during digestion and increase blood glucose levels. Many foods containing carbohydrates also provide dietary fibre, vitamins and minerals. The amount and type of carbohydrate you eat will affect your blood glucose levels.
Simple carbohydrates (sugars) are broken down and released into the bloodstream quickly. They provide a big burst of energy and raise your blood glucose levels, followed by a drop.
Complex carbohydrates provide a sustained release of energy and provide more stable blood glucose levels.
Foods with a low GI (glycemic index) will release the sugar slowly whereas foods with a high GI will release the sugar quickly.
Protein
Protein is a component of every cell in the human body and is necessary for proper growth and development, especially during childhood, adolescence, and pregnancy. It is an important building block of our immune system, helping us to heal and fight off infection. Protein helps your body build and repair cells and body tissue and is a major part of your skin, hair, nails, muscle, bone, and internal organs. It is important for many body processes, such as blood clotting, fluid balance, immune response, vision, and the production of hormones, antibodies, and enzymes. Protein provides calories, or “energy” for the body. Each gram of protein provides 4 calories
Everyone has different protein needs. Your protein needs depend on many factors including if you are losing muscle mass, the presence of disease or infection and physical activity. I generally recommend between 1.2-1.5g/kg.
Fats
Fat is a basic part of cell membranes and is necessary for proper growth and development. It helps the body absorb important fat-soluble vitamins (vitamins A, D, E, and K) and supports key body processes, such as blood clotting, nervous system function, reproduction, and immune response. Fat plays a vital role in maintaining healthy skin and hair. It also provides taste and consistency in food and helps you feel full. Fat provides calories, or “energy,” for the body. Each gram of fat provides 9 calories. Fat also stores energy in excess of what the body needs immediately and serves as a secondary energy source once calories from carbohydrates are used up.
Mono and Polyunsaturated Fats 'Healthy Fats'
Monounsaturated and polyunsaturated fats are found in higher proportions in plants and seafood and are usually liquid at room temperature as oils. The exceptions are certain tropical plant oils, such as coconut oil, palm oil, and palm kernel oil (which are high in saturated fat) and partially hydrogenated oils (a source of artificial trans fat).
Saturated Fats
Saturated fat is found in higher proportions in animal products and is usually solid at room temperature. An exception is seafood, which is generally low in saturated fat.
Trans Fats
Trans fat is an unsaturated fat, but it is structurally different than unsaturated fat that occurs naturally in plant foods. Trans fat has detrimental health effects and is not essential in the diet. It can be found naturally in animal products and also formed artificially during food processing
Cholesterol
Cholesterol is a waxy, fat-like substance found in all cells of the body. Cholesterol is produced by the body (primarily by the liver) and is also consumed from food, referred to as “dietary cholesterol.” It plays an important role in the production of sex hormones, bile and vitamin D and is a structural component of cell membranes
