Macronutrients: Nutrients that are required by your body in daily amounts greater than a few grams such as carbohydrate, fat and protein.
Carbohydrates: consumed in your diet are made of the chemical elements carbon, hydrogen and oxygen. The main role of carbohydrates is energy production. They form your body’s most readily available source of energy and can be accessed rapidly. One gram of carbohydrate, whether this is derived from sugar or starch, will provide you with approximately 4 kilocalories of energy. The carbohydrate foods you eat are divided into two basic types and are generally referred to as either simple or complex.
Simple carbohydrates are essentially sugars and are formed from single and double sugar units. They are easily digested and absorbed to provide your body with a quick energy source. The simplest unit of carbohydrates is the monosaccharide, the most common of which in your diet is glucose. Saccharide means sugar, mono means one; therefore a monosaccharide is a single sugar unit. Glucose is used to produce adenosine triphosphate (ATP), the compound required for muscle contraction.
Longer chains of these simple sugar units are known as polysaccharides or complex carbohydrates. These allow large quantities of glucose to be stored in the cells of plants as starch or in animals as glycogen in the muscles and liver. All carbohydrate consumed in your diet ends up as glucose to provide energy. Complex carbohydrates are commonly known as starches and make up an important source of energy in most diets. They are composed of many sugar units so they are also called polysaccharides. These are broken down more slowly in your body and provide a sustained release of energy over longer periods. Complex carbohydrates should form the largest percentage of your total carbohydrate intake. Unrefined sources such as wholemeal bread, wholegrain rice and pasta are preferable as they also contain a higher nutritional value by way of micronutrients and fibre.
Proteins have a variety of functions that are essential to maintaining optimal health and physical performance body needs all 20 amino acids to be p resent simultaneously for protein synthesis to occur, in order to sustain optimal growth and functioning. Different proteins contain different numbers and combinations of these amino acids. Of the 20, there are eight that your body is unable to make for itself and as a result these are called essential amino acids (EAAs) – they are a necessary part of your diet. The remaining amino acids are called non-essential – your body is able to synthesise these if all the essential amino acids are present.
The chief role of protein in your body is to build and repair tissue. However, proteins may also be used as a secondary source of energy when carbohydrate and fat are limited, such as towards the end of prolonged endurance events or during the severe energy restriction that may accompany dieting.
Proteins, like carbohydrates, have an energy value of approximately 4 kilocalories per gram.
Unlike carbohydrate and fat, your body is unable to store excess protein. All proteins carry out functional roles in your body, so daily protein ingestion is required. If your protein intake exceeds requirements to support growth and repair, the excess amino acids are broken down, the nitrogen component is excreted and the rest of the molecule is used to provide energy immediately or converted to fat or carbohydrate and stored for later use.
Fat: It is important to note that fat is an essential nutrient for your body. Fats, or lipids, are composed of the chemical elements carbon, hydrogen and oxygen, but in different ratios to carbohydrates. The ratio of hydrogen to oxygen is much higher, which explains why fat is a more concentrated source of energy than carbohydrate
Fats consumed in your diet are obtained from both animal and vegetable sources and are of two main types: saturated and unsaturated.
Fatty acids contain chains of carbon atoms to