Cognitive behavioural evaluation and treatment of adolescent overweight and obesity

Brennan, L 2006, Cognitive behavioural evaluation and treatment of adolescent overweight and obesity, Doctor of Philosophy (PhD), Health Sciences, RMIT University.


Document type: Thesis
Collection: Theses

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Title Cognitive behavioural evaluation and treatment of adolescent overweight and obesity
Author(s) Brennan, L
Year 2006
Abstract The prevalence of overweight and obesity in adolescents has increased markedly in recent years. Overweight and obese adolescents are at increased risk of a range of weight related disorders such as type 2 diabetes and cardiovascular disease. These young people are also at increased risk of negative psychosocial outcomes such as weight based discrimination and prejudice, lower self-esteem, disordered eating, and reduced quality of life. As the presence of overweight or obesity in adolescence is also the single best predictor of adult overweight and obesity, treating adolescents may be the most effective way to prevent or reduce adult overweight and obesity and its consequences. Despite these factors, overweight and obesity in adolescence has received very little attention in the scientific literature. Consequently, the psychosocial consequences of excess weight in adolescence have not been thoroughly explored, and few empirically based treatment options exist for this age group.

The major objective of this research program was therefore to evaluate the efficacy of a cognitive behavioural program in the treatment of adolescent overweight and obesity. This comprehensive intervention program incorporated a range of cognitive behavioural techniques aimed at assisting adolescents to establish and maintain healthy eating and physical activity habits. Treatment resulted in improved body composition at post treatment and sustained or improved body composition following maintenance. Despite reductions in weight and body fat, lean body mass was not affected by the intervention, thus, treatment did not detrimentally effect linear growth and lean body tissue. Participation in a motivational interview prior to this cognitive behavioural intervention did not influence treatment outcomes. Of note, BMI based weight classification systems recommended for research and clinical practice did not consistently classify adolescent overweight and obesity, and, weight classification based on BMI criteria was a poor indicator of percent body fat, particularly in males.

Poor compliance with measurement protocols limits conclusions that can be drawn regarding the impact of treatment on eating and activity habits. Despite these limitations results suggest that few treatment seeking adolescents met Australian recommendations for healthy eating and physical activity habits. Treatment resulted in a reduction in fat consumption, reduced saturated fat intake, and reduced time spent in sedentary activities. Increases in physical activity were not evident.

The treatment seeking sample did not report elevated psychopathology levels and treatment did not impact on adolescent depression, anxiety, or stress. Adolescents XXXV receiving treatment reported improvements in disordered eating relative to those in the control condition. Thus, treating adolescent overweight and obesity in a supportive setting did not increase general psychopathology or eating and weight related psychopathology. While adolescent psychopathology was not significantly influenced by treatment participation, 11% of the treatment sample was referred to specialist services for assistance in the management of anxiety or depression. This outcome highlights the importance of assessment and detection of psychopathology in adolescents participating in weight loss interventions.

A secondary aim of this research program was to redress the limited information available on the behavioural and psychosocial factors associated with adolescent overweight and obesity. With this aim in mind the relationship between body weight and psychosocial characteristics in community samples of adolescents and their parents, and young adults were explored. The psychosocial characteristics of the community sample of adolescents were also compared to those of the treatment seeking adolescent sample.

A large number of young adults, adolescents and parents did not report height and weight information. Even with height and weight information many young adults, adolescents and their parents were unable to correctly classify the adolescent/young adult’s weight. The majority of overweight adolescents/young adults were classified as normal weight, and the majority of obese adolescents were classified as overweight (not obese). The impact of cultural body ideals depicting a slim female body and a muscular male body was also evident. There was a tendency for more females to perceive themselves as overweight and males were more likely to perceive themselves as normal or underweight. Both actual and perceived weights were associated with weight discontent in young adult females, and male and female adolescents. Thus, discontent regarding body weight existed in adolescent males but not young adult males. In comparison to both normal and overweight adolescents, treatment seeking adolescents reported greater body dissatisfaction and weight discontent. Results also suggest that while dieting may be an adaptive response to overweight in young adults, dieting may be an indicator of disordered eating and psychopathology in adolescents.

Body weight was not associated with psychopathology in the community samples and treatment seeking adolescents did not differ from normal or overweight adolescents from the community sample in terms of psychopathology. However, young adults who reported being overweight during childhood reported greater XXXVI psychopathology as young adults. These findings suggest that excess weight in adolescence may have longer term rather than immediate effects on psychopathology.

A number of family factors were associated with body weight in both adolescents and young adults. In the community sample maternal weight evidenced one of the strongest relationships with body weight in adolescents and young adults. Heavier adolescents and young adults were more likely to have heavier mothers. Family socioeconomic status was also found to be related to both parent and adolescent weight status.

Findings of this research program are discussed with relation to the methodological considerations and clinical and research implications. Combined, results indicated that CBT is efficacious in the treatment of overweight and obesity in adolescents and MI does not improve the efficacy of CBT. The current findings suggest that the impact of excess weight on psychosocial functioning is limited to body discontent and dissatisfaction in adolescence but is associated with increased psychopathology in early adulthood. Results also highlighted the importance of parents and family in the treatment of overweight and obesity in adolescents. The current findings indicate that a significant proportion of young adults, adolescents and parents did not know, or failed to report, height and weight information. Even with height and weight information, many adolescents and their parents underestimated the adolescent’s weight status. Findings also highlighted a number of difficulties with the measurement of eating and physical activity and the use of BMI criteria to classify adolescent weight status.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Health Sciences
Keyword(s) Adolescent psychology
Obesity -- Psychological aspects
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