Introduction
obesity, illness, anxiety, pain, overweight, disordered eating, depression, disability
OBESITY, CHRONIC CONDITIONS, DISEASE, SEVERE OBESITY, SECONDARY
Chronic health conditions, characterised by their long-lasting and persistent effects, are a substantial cause of disability and disease burden [There is growing evidence that psychological treatment, especially cognitive behavioural therapy (CBT) can promote adjustment to illness in people with chronic health conditions, such as improvements in functioning and psychological wellbeing [Less is known about the effects of psychological treatment, including both face-to-face CBT and iCBT, in people with co-occurring chronic health conditions and high weight (i.e. obesity or overweight), despite their frequent overlap, and their common clustering with poor mental health. In a multidisciplinary pain rehabilitation program with a considerable psychological component, program participants with severe obesity (BMI ≥ 35) showed the least improvement in health-related quality of life, although they showed similar improvements in anxiety and depression to those within lower weight ranges [The current study sought to examine the associations between BMI range and the clinical outcomes of a randomised controlled trial (RCT) of an iCBT program aiming to promote adjustment to illness in adults with chronic health conditions, based on cognitive behavioural therapy principles (the Chronic Conditions Course [In this program, the treatment group reported statistically and clinically significant improvements in the primary outcomes (depression, anxiety, and disability) compared to a treatment-as-usual control group, with high completion rates and level of satisfaction. In the current study, secondary analyses examined associations between baseline BMI range and treatment response at post-treatment and 3-month follow-up, as well as changes in weight and self-rated impact of weight on health between pre-treatment and 3-month follow-up. Given some evidence of reduced response to treatment in people with obesity, it was hypothesised that (1) higher BMI range at baseline would predict poorer treatment response for depression, anxiety, self-reported disability and life satisfaction at post-treatment and at 3-month follow-up, and that (2) BMI and its self-reported health impact would not shift between pre-treatment and 3-month follow-up, due to the fact that the intervention did not specifically target factors generally considered to be implicated in the maintenance of obesity and overweight (such as diet, formal instructions for exercise, shape and weight concerns, and disordered eating).