Consideration of these many influences helps in the development of nutrition programmes and the implementation of health education messages. Understanding how people make decisions about their health can also help in planning health promotion strategies. This is where the influence of social psychology and its associated theory-based models play a role. These models help to explain human behaviour and can be used to predict the likelihood that behaviour such as dietary change will occur.

Health Behavioural Models

Several theories have attempted to explain the influence of different variables on the individual’s health related behaviour and the elements that are important in influencing people to change. These include: the Health Belief model and the Protection Motivation theory (which suggests that people need some kind of cue to take action to change behaviour or make a health–related decision), the Theory of Reasoned Action and the Theory of Planned Behaviour (based on the hypothesis that the best predictor of the behaviour is behavioural intention) and the Stages of Change model (or The Transtheoretical Model). This article will focus on the “Stages of Change” model, since it is probably the best known model in the field of dietary change.

Stage classification for health-related behaviour

The model is based on change being an ongoing cycle and not being final. People may relapse to earlier stages several times, but this does not necessarily mean they start all over again. Thus, subjects are described in terms of their progress through a series of behavioural states along with other related dimensions such as self-confidence to change. This information can be taken into account in tailoring education messages to subjects’ needs and readiness for various types of information.

Limitations associated with the “Stages of Change” model

Despite its popularity this model has also some shortcomings. For instance no consensus has been reached regarding the most appropriate method for defining and measuring dietary stage 2. Another criticism is that the use of fixed time-frames to distinguish between stages neglects to appreciate any gradual change in behaviour. A stage model may be more appropriate for simpler more discrete behaviours such as eating five servings of fruit and vegetables every day, or drinking low-fat milk (food-based goals) than for complex dietary changes such as low-fat eating (nutrient-based goal) 3. Thus, other behavioural models may prove more appropriate for complex goals such as dietary fat reduction.

Nevertheless, the model has been used to understand dietary changes and can distinguish groups with clearly different attitudes towards dietary health. The best test of this model is whether stage-matched dietary interventions outperform standardised approaches.

Presently, no one theory or model sufficiently explains and predicts the full range of food-choice behaviours and it is essential to continue the research in this field 4 Models in general should be viewed as a means to understanding the factors influencing individual decisions and behaviour, which can help in planning appropriate health promotion interventions.

MORE INFORMATION

Please consult our EUFIC Review N° 17.

References

• Prochaska JO, DiClemente CC & Norcross JC (1992) In search of how people change: Applications to addictive behaviours. American Psychology 47: 1102-1114.
• Kristal AR, Glanz K, Curry SJ, Patterson RE (1999) How can stages of change be best used in dietary interventions? Journal of American Dietetic Association 99: 679-684.
• Horwath CC (1999) Applying the transtheoretical model to eating behaviour change: challenges and opportunities. Nutrition Research Reviews 12: 281-317.
• Nestle M, Wing R, Birch L, DiSogra L, Drewnowski A, Arbor A, Middleton S, Sigman-Grant M, Sobal J, Winston M, Economos C (1998) Behavioural and social influences on food choice. Nutrition Reviews 56(5): S50-S64.

FOOD TODAY 02/2005