Nutrition is the science of food, diet, and their effect on the human body. A person’s diet plays an important role in their overall health, as the body needs certain nutrients in order to perform certain functions. Nutrients are categorised in different groups. Carbohydrates, fibre, fats, protein and water are considered to be macronutrients whereas vitamins and minerals are classed as micronutrients. To ensure that the suggested amount of each food group is ingested, it is recommended that people follow a healthy, balanced diet. There are many disputes between nutritionists over what constitutes a healthy, balanced diet. Furthermore, each individual is different and has different needs. For example, athletes, pregnant women and people recovering from illness will all have unique dietary requirements. However, there is a general consensus over certain principles of healthy eating: to eat plenty of fruit and vegetables as they are full of vitamins and minerals and it is advised that we should eat five portions a day, which should make up just over a third of the food we eat each day; to not eat too much sugar or saturated fat as having a high sugar intake increases the risk of obesity and tooth decay, particularly for people who regularly drink sugary, fizzy drinks; to eat starchy carbohydrates, ideally wholegrain, as potatoes, bread, rice and pasta (ideally wholegrain) are a great source of energy; to eat lean sources of protein such as fish, eggs, beans, pulses and lean meat; to drink plenty of liquid (6-8 cups or glasses a day) as keeping hydrated is essential to good health. Poor diet can cause a wide range of health problems and conditions resulting from malnutrition or from eating too much of a particular food group (such as fat and sugar), including obesity, diabetes, blindness, anaemia, scurvy, cardiovascular disease, osteoporosis.