Why are some people more successful at lifestyle change than others? Factors associated with successful weight loss in the BeWEL randomised controlled trial of adults at risk of colorectal cancer.

BACKGROUND: The BeWEL (BodyWEight and physicaL activity) randomised controlled trial demonstrated that a weight management programme offered in the colorectal cancer screening setting was effective. However, the differential responses of participants to the programme were notable. This study aimed to explore the factors associated with success and to identify implications for future programme design.

METHODS: Analyses were conducted of quantitative data (n = 148) from the BeWEL intervention group to compare demographic and psychosocial characteristics and lifestyle changes in those who met and exceeded the target 7% weight loss ('super-achievers') with those who achieved only 'moderate' or 'low' amounts of weight loss (2-7% loss, or <2% loss, respectively). In-depth qualitative interviews (n = 24) explored in detail the motivations, actions, pathways to weight loss and circumstances of study participants.

RESULTS: Over the 12 month intervention period, mean percentage weight loss of super-achievers (n = 33) was 11.5%, compared with moderate-achievers (n = 58) who lost 4.2%, and low-achievers (n = 57) who gained 0.8%. Compared to other groups, super- achievers increased their fruit and vegetable intake (p < 0.01) and physical activity (step count, p < 0.01). 'Super-achievers' did not differ in baseline demographic characteristics from other participants. However, significantly fewer reported that their activities were limited by physical and emotional health and they were more likely to perceive their current diet as harmful. Qualitative analyses found no consistent patterns among super-achievers in relation to some factors identified as important in previous studies, such as social support. However, super-achievers shared several characteristics such as determination and consistency in their engagement with the intervention, receptivity to new information and prompts, previous positive experience of changing health behaviours, being motivated by early success, making changes routine, and an ability to devise and apply strategies for dealing with setback and 'relapse' triggers.

CONCLUSIONS: Successful lifestyle change depends on active engagement as well as effective intervention ingredients. Weight loss interventions are likely to be more effective where they can adapt to participants' differing characteristics and needs, while also providing core elements likely to build success.