An investigation into whether a small change approach is an effective strategy for weight management

The prevalence of overweight and obesity continues to rise in England, which has detrimental impacts on health, society and the economy. To date, weight management strategies have been ineffective at reducing the prevalence of overweight and obesity within the population. This highlights that alternative weight management strategies should be considered. An alternative weight management strategy that could help people manage their weight is a small change approach, which recommends people should decrease their energy intake and/or increase their energy expenditure by 100-200 kilocalories per day. This thesis aimed to investigate whether a small change approach could be an effective strategy for weight management.A systematic review and meta-analysis of randomised controlled trials that tested a small change approach for weight management was conducted to summarise the existing evidence and provide direction for the remaining PhD research as well as recommendations for research beyond the thesis. The systematic review and meta-analysis found adults who used a small change approach gained 0.9 kg (95% CI: -1.5 to -0.3) less than those in comparator groups over ~14 months. However, this effect was pooled from randomised controlled trials that mostly delivered a small change approach within intensive interventions (involving multiple face-to-face contacts). Additionally, none of the studies included in the systematic review considered participants’ views about the potential merits and difficulties of using a small change approach for weight management.To bridge the research gaps identified in the systematic review, a small change intervention suitable for delivery at scale was then developed, evaluated and tested in a feasibility randomised controlled trial. A nested qualitative study was also included to gain a more in-depth understanding of participants’ views about implementing a small change approach to prevent weight gain. Participants who received the intervention gained 1.1 kg (95% CI: -1.7 to -0.4) less than those in the comparator group. Participants generally expressed positive views about the small change approach for preventing weight gain and reported that it helped them to form new weight management habits. However, some participants found this approach difficult to implement in certain contexts.<br>