There are two main sections to this topic.
The food section basically talks about how to eat a balanced diet and really has a lot about nutrition. You can refer to the food technology section for this but in biology it is simpler and you don't need to know as much =)
To start the topic off I will explain the term 'a balanced diet'
There are five groups of food substances that you must include in your diet (also explained in the food technology section)
If the food you eat provide you with all these substances in the right amounts and proportions, you are eating a balanced diet.