In contrast above we have an example of an opposing relationship also expressed in Jamie's manifesto. It says: the quality of diet affects obesity in the opposite direction all other things being held equal. That is to say, a better diet leads to less obesity and a poorer diet leads to more obesity.

Putting the two relationships together shows us that nutritional knowledge affects diet which in turn affects obesity.

We can dig deeper by asking ourselves the questions “what else” has an impact and “how”. For example, what else affects quality of diet and how? What affects obesity and how? In this way we can develop a detailed diagram of how we believe the system we are considering works.

As we dig deeper we encounter feedback. This is a group of variables related to each other in a loop or cycle. An example can be seen below.