One of the key features of our diet is to provide the energy we require for our bodies to function. Energy comes from three key components of our diet. These are;
- carbohydrates, found in rich supply foods such as grains, rice, starchy vegetables and sugary foods,
- proteins, found in foods such as meat and fish
- fats, found in foods such as oils, nuts and animal fats.
Gram for gram, we can gain the same amount of energy from proteins as carbohydrates and we can gain up to nine times as much energy from fats. However, proteins are also required by the body for other purposes, whilst the utilisation of fats can lead to other problems such as high circulating levels of cholesterol, so carbohydrates are often considered to be the mainstay of energy provision.
On average a man requires about 2500 Kcalories a day and a woman about 2100 Kcalories. However, the amount of energy we actually need is dependent on a number of things. Our level of activity is one of the most important. The more active we are, the more energy we require. Age is also a significant factor. In later life our requirement for energy generally decreases, but this is related to changes in activity levels, health, and mobility rather than changes in metabolism alone. Children and adolescents also have different energy requirements to adults and these reflect body size and growth.