摘要：We conducted a systematic review and meta-analysis investigating the components and effectiveness of self-help weight-loss interventions and their applicability to less-advantaged populations. We searched (November 2013) for randomized controlled trials comparing self-help interventions with each other or with minimal controls in overweight and obese adults, with 6 months or longer follow-up. We calculated mean difference between intervention and control for 6- and 12-month weight change. Twenty-three studies met the inclusion criteria (9632 participants; 39 intervention arms). Intervention participants lost significantly more weight than controls at 6 months (mean difference −1.85 kg; 95% confidence interval [CI] = −2.86, −0.83; 7 studies). No significant effect was detected at 12 months but results were sensitive to the inclusion of 1 study at high risk of bias. Interactive programs appeared more effective than standard ones at 6 months (mean difference −0.94 kg; 95% CI = −1.50, −0.38). Evidence is insufficient to reach conclusions on effectiveness in socioeconomically disadvantaged people, but suggests self-help interventions may be less effective in this group. Overweight and obesity are a major cause of preventable morbidity and mortality worldwide, with the World Health Organization estimating that they cause at least 35.8 million disability-adjusted life years and 2.8 million deaths annually. 1 At any one time, more than a quarter of US women are trying to lose weight (27%), with men not far behind (22%), the large majority of whom are doing so without professional support and outside the context of formal weight-loss programs. 2 By contrast with more intensive interventions, 3–5 very little is known about these self-directed efforts to lose weight. The high prevalence of overweight and obesity presents a resource challenge to health care systems. Trials of self-help interventions for weight loss can inform our knowledge about what types of self-directed weight loss strategies are most effective and which might be usefully highlighted to the public as a scalable, low-cost public health intervention. Moreover, understanding the effective components of self-help interventions for weight loss may enable future tailoring of other weight management programs to enhance effectiveness. Interventions that are self-directed and do not require professional input to deliver (“self-help”) come in a variety of formats, including but not limited to print, Internet, and mobile phone–delivered programs. Data from the past 5 years suggest that such interventions are being widely used: 33% of US Internet users look online for information about weight management and 19% of smartphone owners are estimated to have a health app on their phone, with the most popular type being diet, exercise, and weight apps. 6–8 Most reviews of trials of self-help interventions for weight loss are defined by the format of the programs rather than the content. 9–11 Results from format-specific reviews suggest that such interventions may be promising, but results across these reviews are mixed. In addition, there is limited research on the longer-term effectiveness of these efforts, with longer-term data frequently only emerging from uncontrolled program evaluations. 11 Moreover, this format-specific focus, though informative for questions about delivery medium, limits the opportunity to examine the behavioral components across format types, and also leads to the inclusion of some more resource-intensive interventions alongside true self-help programs. For example, some Internet interventions may include input from trained personnel. We therefore conducted a systematic review of self-help interventions across all relevant formats, but limited to those that do not require professional input to deliver. It is also possible that the effectiveness of self-help interventions could vary by population group. 12 In middle- and high-income countries, obesity is more common among lower socioeconomic groups, 13,14 but there is concern that some interventions tackling obesity are taken up more effectively by more advantaged groups, thus further widening existing inequalities. 15 Of particular relevance to this review, it may be that self-help programs are more effective for socioeconomically advantaged groups. There are a number of possible mechanisms through which socioeconomic status (SES) may influence the effectiveness of self-help programs. Executive functioning, a theorized control network regulating behaviors, has been linked with poverty in childhood, with more disadvantaged groups associated with lower strength of executive functioning in adulthood. Weaker executive functioning could conceivably diminish an individual’s ability to enact the recommended actions in self-help programs, as lower levels of executive functioning have been found to be associated with uncontrolled eating and a lower level of inhibitory control. 16,17 It has also been theorized that cultural capital, expressed through certain attitudes, knowledge, and competencies, may increase the ability of more socioeconomically advantaged groups to enact behavior change to improve health outcomes, whereas the corresponding lack of cultural capital may diminish health-related behavior change in less-advantaged populations. 18 In addition, it may be that the environmental factors that contribute to higher levels of obesity in socioeconomically disadvantaged groups provide further barriers to responding to the recommended actions in self-help programs, including issues such as access to healthy food and safe and affordable recreation. 19,20 Accordingly, the provision of self-help materials, which draw on executive functioning and cultural capital to effect change in health outcomes, could exacerbate existing health disparities by leading to greater weight loss in more socioeconomically advantaged groups while having less of an impact on disadvantaged groups. The aims of this review, therefore, were 3-fold. We set out to evaluate the effectiveness of self-help interventions for weight loss in overweight and obese adults and to identify the most effective components in terms of behavioral processes. We then looked at data on socioeconomic variables to assess if the observed effects were likely to be transferable to both socioeconomically disadvantaged and advantaged populations.
