Perceptions of obesity as a health risk: psychometric scale development and relationship with behavioural intentions

Abstract

Obesity represents a serious threat to health which can be reduced by volitional control of eating and physical activity behaviour. Social cognition theories propose that such behaviour is influenced by cognitions regarding its desirability. The role of obesity outcome expectancies in predicting weight control behaviour has not been established and there are no psychometrically sound measures of these constructs. This thesis aimed to investigate the relationship between knowledge and beliefs regarding obesity's consequences and weight control Intentions in obese patients. The Obesity Risk Knowledge Scale (ORKS-10) was developed using item analysis and rigorously evaluated in a large population (n=965). The ORKS-10 scale proved to be a short, reliable and valid measure of knowledge regarding the health risks associated with obesity. In addition, thematic analysis of data from focus groups and structured interviews was used to identify 41 salient items for a scale to measure obesity outcome expectancy beliefs. Factor and item analysis were then used to develop the Obesity Outcome Expectancy Beliefs Scale (ObEx-15). The ObEx-15 comprises three reliable and unidimensional subscales; the Health Benefits of Weight Control (HBen), Social and Aesthetic Benefits of Weight Control (SABen) and Costs of and Barriers to Weight Control (Cost). Obese adults were recruited from weight management clinics (n=110, response rate=54.19%). Multiple regression analysis indicated that weight control intentions were most strongly associated with endorsement of the social and aesthetic consequences of obesity (B=0.117, t104=2.314, p<0.05) and rejection of the costs and barriers of weight control (B=0.088, t104=2.273, p<0.05). Participants had low levels of knowledge about obesity's health risks and neither ORKS-10 scores nor HBen scores were associated with intentions. Health promotion might, therefore, benefit from focusing upon obesity's non-health impacts and the costs and barriers of weight control. Future obesity outcome expectancies research will also profit from the availability of psychometrically sound measures