Introduction to nutrition

Nutrition is defined as the processes by which an animal or plant takes in and utilises food substancesEssential nutrients include protein, carbohydrate, fat, vitamins, minerals and electrolytes. Normally, 85% of daily energy use is from fat and carbohydrates and 15% from protein. In humans, nutrition is mainly achieved through the process of putting foods into our mouths, chewing and swallowing it. The required amounts of the essential nutrients differ by age and the state of the body, for example: physical activity, diseases present (e.g. prostate cancer, breast cancer or weakened bones – known as osteoporosis), medications, pregnancy and lactation.

Why is nutrition important?

Nutrition is essential for growth and development, health and wellbeing. Eating a healthy diet contributes to preventing future illness and improving quality and length of life. Your nutritional status is the state of your health as determined by what you eat. There are several ways of assessing nutritional status, including anthropometric (i.e. physical body measurement), food intake and biochemical measurement.

The healthy weight range for adults of a BMI of 20 to 25 is not a suitable measure for children.
BMI and children

For adults who have stopped growing, an increase in BMI is usually caused by an increase in body fat. But as children grow, their amount of body fat changes and so will their BMI. For example, BMI usually decreases during the preschool years and then increases into adulthood.

For this reason, a BMI calculation for a child or an adolescent must be compared against age and gender percentile charts. These charts should be used only by health professionals such as your general practitioner, child health nurse, or dietitian.