Water

It falls from the sky (maybe a bit too often!).We swim and play in it. We wash in it. We take it for granted.

Our bodies are between fifty and sixty percent water, depending on gender. Every single cell of the body needs water to function optimally. Water helps the body get rid of toxins. Without adequate water the body's metabolism (how it burns fat) slows down - the same as it would if you skipped a meal. We need water to absorb and circulate the water-soluble vitamins (eight 'Bs' and 'C'). Water in the body helps control body temperature and aids in weight loss. It's required for proper digestion. Water is refreshing and contains no kilojoules, and it's as good as free (from the tap, at least).

A lot (if not all) diets want you to drink upwards of eight glasses of water a day, and if you aren't going to drink anything else it's probably do-able. But most of us still enjoy our morning cuppa - I know I can't do without mine. We actually need about two and a half litres of fluid a day. Approximately one litre will come from the food we eat, but the rest has to be ingested in some form of liquid.

If you live in a hot climate, you do strenuous exercise, or you are pregnant or breastfeeding, then you will need more liquid, and water is by far the best available. Don't let yourself get thirsty. By the time you consciously register that you are thirsty, you are already two percent dehydrated. Dehydration can lead to headaches, lethargy, difficulty concentrating and dizziness. You can go without food for two to three weeks, but going without water (liquids) will kill you in under one week.

Babies and toddlers have a less developed sense of thirst than adults, so they need to be encouraged to drink water in order to maintain a constant body temperature, especially after exercise. Set an example. It'll be good for the children and good for you.