Health professionals are usually very keen to provide patients and the public with information and advice on healthy behaviour. Such enthusiasm leads to the production of leaflets, posters, campaigns and other methods of raising people’s awareness and knowledge of health risks and healthy lifestyles, from what constitutes a healthy diet to warnings about catching AIDS. Providing such information in accessible formats is essential, but is not enough on its own to reliably produce behaviour change, which is strongly influenced by external, environmental and social factors.

The knowledge–attitudes–behaviour (KAB) model is one approach to changing behaviour in individuals; knowledge of a health risk and how to avoid or minimise it is expected to change behaviour towards a healthier lifestyle. There is a well-recognised gap, however, between knowledge of a health risk and taking action to avoid it, well illustrated by smoking: few people openly deny that smoking is harmful to health, but a substantial proportion of the population continues to smoke on a regular basis. The health belief model suggests that people will change their behaviour to avoid a specific risk to their health if they believe that the risk is serious, that they themselves are likely to get the condition and that there is action they could take to avoid or minimise the risk, the benefits of which outweigh the costs.

The transtheoretical model