Background: The prevalence of overweight and obesity continues to gradually increase each year with worldwide obesity recorded to be more than double since 1980. Despite the significance placed on lifestyle interventions for obesity management, most weight loss is followed by weight regain. In fact, people who have lost weight on lifestyle programmes, regain approximately 40% of the weight they lose in the first year after losing it and much of the rest in the following three years. Recently, psychological concepts of habitual behaviour
and automaticity have been suggested as plausible explanations for this overwhelming lack of long-term weight loss success. Consequently, habit-based interventions are becoming a novel and emerging strategy to help reduce excess weight in individuals with overweight or obesity Aims: This thesis aimed to determine the efficacy of habit-based interventions for weight loss and weight loss maintenance in adults with overweight or obesity. Methods: Four interrelated studies were conducted using a variety of research methods. Firstly, a formative literature review collated and describe the current evidence on eight
management interventions including the role of habits in weight loss maintenance. Secondly, a randomised controlled trial assessed the efficacy of two habit-based interventions on weight loss and weight loss maintenance. This was followed by a qualitative study using semistructured interviews to explore the general experience of a sub-sample of participants from the two-habit-based interventions implemented in the RCT. Lastly, we conducted a systematic
review and meta-analysis to determine the weight loss and weight loss maintenance outcomes of habit-based interventions compared with active and non-active control groups. Results: The initial study found that habit-based interventions show promising results in sustaining behaviour change. Weight loss maintenance may benefit from incorporating habitfocused strategies and should be investigated further. The RCT included 75 adults with a mean BMI of 34.5kg/m2 (SD 6.2). After a 12-week intervention period, participants in the habit-based programs lost significantly more weight (combined mean -3.1kg) than those in the waitlist control group (-0.4kg) (P= <0.001). At 12-months post-intervention, participants in the habitbased interventions maintained their weight loss and achieved further weight loss (combined mean from baseline -5.1kg), with 65% (28/43) of participants reducing their total body weight by ≥5%; a clinically important change. The third study revealed five key themes relating the participants’ general experience on the habit-based weight loss programs: (i) novelty of interventions and outcomes, (ii) convenience and practicality, (iii) indirect health benefits and wellness, (iv) accountability and (v) sustained behaviour change. Participants reported a positive experience whilst on the habit-based programs, highlighting it was refreshing to not
focus on diet and exercise. Participants also reported that the benefits continued long after the interventions had concluded; these included weight loss maintenance, general wellbeing, selfefficacy and sustained behaviour change, among others. Finally, the systematic review included five trials (630 participants) and showed a statistically significant difference in weight loss outcomes between habit-based interventions (range 8-14 weeks duration) and control groups (-1.4kg [95% CI -2.3, -0.5; P= 0.004]). Participants in the intervention groups were 2.4 times more likely to achieve clinically beneficial weight loss post-intervention than control participants. The was no statistically significant difference however at follow-up (range 6-24 months post-intervention), when we compared habit-based interventions with active control groups (-0.1kg [95% CI -2.5, 2.4; P= 0.96]). When observing single-armed results, four of the five included studies showed that habit-based interventions were successful at achieving weight loss maintenance.
Conclusions and Implications: The results of these studies highlight that habit-based weight loss programs are more effective at achieving clinically beneficial weight loss than lifestyle advice, non-habit based programs and waitlist groups in the short-term but these effects are not sustained when active weight loss programs are compared with habit-based programs over the long-term. Longer studies that are powered to examine at least a 12-month follow-up are required to evaluate weight loss maintenance. Habit-based programs are however practical and convenient for individuals to implement and offer a refreshing alternative to diet and exercise advice. Therefore, habit-based weight loss interventions offer health professionals and clinicians a useful tool for incorporating evidence-based health promotion with individuals desiring sustained benefits.