Our bodies are always active - from before we are born until the day we die.
Even when we're asleep our hearts continue to beat, we keep on breathing, and the cells that make up our bodies are constantly being repaired and renewed.
All of this activity requires a supply of energy and a source of raw materials.
Both of these things come from the food we eat. This book explains the importance of nutrition, and shows how things like appetite and the foods we want and need change during our lives.