Date of Submission
Thomas, K. N. (2012). An investigation of the pertinent factors associated with overweight and obesity (Doctoral thesis, Australian Catholic University). Retrieved from https://doi.org/10.4226/66/5a96268fc6885
The prevalence of obesity is increasing at such an alarming rate worldwide that the World Health Organisation (WHO) has declared it a global epidemic. Recent epidemiological data from WHO forecasts that by 2015, approximately 2.3 billion people will be overweight or clinically obese. Obesity is stigmatised on both health and aesthetic grounds, and is associated with serious health impairments, psychosocial consequences, and a shortened life span. As a result, eating pathology has become a central focus of current health prevention. Adding further strain to the pandemic is the pervasive finding that obesity is largely resistant to treatment. Research has shown that losing 5-10% of body weight produces significant physical and psychosocial effects, provided the weight-loss is maintained. However, extant research has consistently found that weight-loss is almost always regained over time. Participants in obesity treatment programs typically regain approximately 50% in the first year following the cessation of treatment, and by three to five years following treatment, 80% of participants have regained all of the weight lost, and have frequently exceeded their pre-treatment weight. These results have necessitated new approaches to the treatment of obesity. Recent research has revealed that targeting the psychological factors associated with body weight and training individuals in acceptance and mindfulness skills have been effective for weight-loss. The aims of this thesis were twofold. First, it aimed to investigate the pertinent factors that are associated with overweight and obesity. Second, it aimed to examine the efficacy of a pilot obesity treatment program using dialectical behaviour therapy principles. Three studies are included in this thesis. First, a broad range of biological, social, environmental, and psychological factors that have been shown to be associated with body weight were explored. The results from Study 1 indicated that the psychological influences on body weight were the most pertinent factors differentiating healthy weight individuals from overweight and obese individuals. In particular, overweight and obese individuals demonstrated lower levels of self efficacy for weight related and health behaviours, greater difficulty in controlling overeating in response to negative affect and to different social contexts. Moreover, overweight and obese participants were shown to be less likely to employ self monitoring techniques. Subsequently, Study 2 investigated additional psychological factors by examining whether there were differences between healthy weight individuals and overweight and obese individuals with regard to self-esteem, body esteem, and sociocultural attitudes towards appearance. The findings from this study revealed that body esteem was the most prominent factor distinguishing healthy weight individuals from their overweight or obese counterparts. Thereafter, the results of Study 1 and Study 2 formed the rationale for the development of a pilot DBT-informed obesity treatment program using six case studies. Study 3 investigated whether dialectical behaviour therapy may be useful in addressing these psychological factors to achieve slow weight-loss that can be maintained over time. There were four main findings from this study. First, the trend in scores highlighted a positive link between body esteem and weight-loss. As participants lost weight over time, their satisfaction with body weight and appearance also increased. Second, five out of six participants demonstrated an increase in self-monitoring, which suggests that self-monitoring of weight and health-related behaviours is relevant to weight-loss. Third, the results reveal that a two-day workshop is insufficient time to adequately address the negative emotions that individuals reported experiencing. Finally, five out of six participants demonstrated weight-loss between baseline and six-months post-treatment. Notably, two participants from the treatment group reported substantial weight-loss of nine kilograms and twelve kilograms. Participants in the active control group reported small weight-loss of two kilograms, three kilograms, and five kilograms, respectively. These results suggest that the treatment had some impact on weight-loss, although it is unknown which aspect of the treatment that may be. It is recommended that future research use a randomised controlled trial to investigate the efficacy of a DBT-informed of longer duration with a large sample size, expert DBT clinicians facilitating the treatment groups, and exclude comorbid mental health disorders. While it is expected that obesity treatments will continue to improve, a focus on prevention and early intervention is recommended to halt the current global obesity epidemic.
School of Psychology
Doctor of Philosophy (PhD)
Faculty of Arts and Sciences