Eliana V. Carraça

Exercise, physical activity, and self-determination theory: A systematic review

BackgroundMotivation is a critical factor in supporting sustained exercise, which in turn is associated with important health outcomes. Accordingly, research on exercise motivation from the perspective of self-determination theory (SDT) has grown considerably in recent years. Previous reviews have been mostly narrative and theoretical. Aiming at a more comprehensive review of empirical data, this article examines the empirical literature on the relations between key SDT-based constructs and exercise and physical activity behavioral outcomes.MethodsThis systematic review includes 66 empirical studies published up to June 2011, including experimental, cross-sectional, and prospective studies that have measured exercise causality orientations, autonomy/need support and need satisfaction, exercise motives (or goal contents), and exercise self-regulations and motivation. We also studied SDT-based interventions aimed at increasing exercise behavior. In all studies, actual or self-reported exercise/physical activity, including attendance, was analyzed as the dependent variable. Findings are summarized based on quantitative analysis of the evidence.ResultsThe results show consistent support for a positive relation between more autonomous forms of motivation and exercise, with a trend towards identified regulation predicting initial/short-term adoption more strongly than intrinsic motivation, and intrinsic motivation being more predictive of long-term exercise adherence. The literature is also consistent in that competence satisfaction and more intrinsic motives positively predict exercise participation across a range of samples and settings. Mixed evidence was found concerning the role of other types of motives (e.g., health/fitness and body-related), and also the specific nature and consequences of introjected regulation. The majority of studies have employed descriptive (i.e., non-experimental) designs but similar results are found across cross-sectional, prospective, and experimental designs.ConclusionOverall, the literature provides good evidence for the value of SDT in understanding exercise behavior, demonstrating the importance of autonomous (identified and intrinsic) regulations in fostering physical activity. Nevertheless, there remain some inconsistencies and mixed evidence with regard to the relations between specific SDT constructs and exercise. Particular limitations concerning the different associations explored in the literature are discussed in the context of refining the application of SDT to exercise and physical activity promotion, and integrating these with avenues for future research.

Mediators of Weight Loss and Weight Loss Maintenance in Middle-aged Women

Long‐term behavioral self‐regulation is the hallmark of successful weight control. We tested mediators of weight loss and weight loss maintenance in middle‐aged women who participated in a randomized controlled 12‐month weight management intervention. Overweight and obese women (N = 225, BMI = 31.3 ± 4.1 kg/m2) were randomly assigned to a control or a 1‐year group intervention designed to promote autonomous self‐regulation of body weight. Key exercise, eating behavior, and body image variables were assessed before and after the program, and tested as mediators of weight loss (12 months, 86% retention) and weight loss maintenance (24 months, 81% retention). Multiple mediation was employed and an intention‐to‐treat analysis conducted. Treatment effects were observed for all putative mediators (Effect size: 0.32–0.79, P < 0.01 vs. controls). Weight change was −7.3 ± 5.9% (12‐month) and −5.5 ± 5.0% (24‐month) in the intervention group and −1.7 ± 5.0% and −2.2 ± 7.5% in controls. Change in most psychosocial variables was associated with 12‐month weight change, but only flexible cognitive restraint (P < 0.01), disinhibition (P < 0.05), exercise self‐efficacy (P < 0.001), exercise intrinsic motivation (P < 0.01), and body dissatisfaction (P < 0.05) predicted 24‐month weight change. Lower emotional eating, increased flexible cognitive restraint, and fewer exercise barriers mediated 12‐month weight loss (R2 = 0.31, P < 0.001; effect ratio: 0.37), but only flexible restraint and exercise self‐efficacy mediated 24‐month weight loss (R2 = 0.17, P < 0.001; effect ratio: 0.89). This is the first study to evaluate self‐regulation mediators of weight loss and 2‐year weight loss maintenance, in a large sample of overweight women. Results show that lowering emotional eating and adopting a flexible dietary restraint pattern are critical for sustained weight loss. For long‐term success, interventions must also be effective in promoting exercise intrinsic motivation and self‐efficacy.

Exercise autonomous motivation predicts 3-yr weight loss in women.

PURPOSE This study evaluated exercise-related predictors of successful long-term weight control in women by analyzing the extent to which sustained exercise participation and self-determination theory (SDT)-based exercise motivation variables mediated the impact of a behavioral weight control intervention on 3-yr weight change. METHODS Longitudinal randomized controlled trial consisting of a 1-yr SDT-based intervention and a 2-yr follow-up with 221 female participants (means ± SD: age = 37.6 ± 7 yr, body mass index = 31.6 ± 4.1 kg·m(-2)). The tested model incorporated experimentally manipulated perceived need support, motivational regulations, and 2-yr exercise adherence as mediators of the interventions impact on 3-yr weight change. Paths were tested using partial least squares analysis. Where there were significant intervening paths, tests of mediation were conducted. RESULTS Treatment had significant effects on 1- and 2-yr autonomous regulations, 2-yr physical activity, and 3-yr weight change, fully mediated by the tested paths (effect ratio = 0.10-0.61). Moderate and vigorous exercise at 2 yr had a significant effect (P < 0.001) on weight loss success at 3 yr and partially mediated the effect of treatment on weight change. The 2-yr autonomous regulation effects on follow-up weight change were only partially mediated by physical activity (effect ratio = 0.42). CONCLUSIONS This application of SDT to physical activity and weight management showed that not all types of motivation predict long-term behavioral outcomes and that sustained moderate and vigorous exercise mediated long-term weight change. It provides strong evidence for a link between experimentally increased autonomous motivation and exercise and long-term weight loss maintenance. Results highlight the importance of interventions targeting the internalization of exercise behavioral regulation and making exercise and physical activity positive and meaningful experiences rather than simply focusing on immediate behavior change in overweight/obese women.

Body image change and improved eating self-regulation in a weight management intervention in women

BackgroundSuccessful weight management involves the regulation of eating behavior. However, the specific mechanisms underlying its successful regulation remain unclear. This study examined one potential mechanism by testing a model in which improved body image mediated the effects of obesity treatment on eating self-regulation. Further, this study explored the role of different body image components.MethodsParticipants were 239 overweight women (age: 37.6 ± 7.1 yr; BMI: 31.5 ± 4.1 kg/m2) engaged in a 12-month behavioral weight management program, which included a body image module. Self-reported measures were used to assess evaluative and investment body image, and eating behavior. Measurements occurred at baseline and at 12 months. Baseline-residualized scores were calculated to report change in the dependent variables. The model was tested using partial least squares analysis.ResultsThe model explained 18-44% of the variance in the dependent variables. Treatment significantly improved both body image components, particularly by decreasing its investment component (f2 = .32 vs. f2 = .22). Eating behavior was positively predicted by investment body image change (p < .001) and to a lesser extent by evaluative body image (p < .05). Treatment had significant effects on 12-month eating behavior change, which were fully mediated by investment and partially mediated by evaluative body image (effect ratios: .68 and .22, respectively).ConclusionsResults suggest that improving body image, particularly by reducing its salience in ones personal life, might play a role in enhancing eating self-regulation during weight control. Accordingly, future weight loss interventions could benefit from proactively addressing body image-related issues as part of their protocols.

Physical Activity Predicts Changes in Body Image during Obesity Treatment in Women

PURPOSE This study examined effects of a behavioral weight management intervention on body image (evaluative and investment dimensions) and explored the potential mediating role of structured and lifestyle physical activity (PA). METHODS The study was a longitudinal randomized controlled trial, including a 1-yr behavior change intervention and a 2-yr follow-up (225 women, 37.6 ± 7 yr, body mass index = 31.5 ± 4.1 kg·m). Statistical analyses comprised mixed-design ANOVAs with repeated measures, bivariate/partial correlations, and mediation analyses. RESULTS Body image improved considerably in both groups, favoring the intervention group (small to moderate effect sizes: 0.03-0.05), but began to deteriorate from 12 to 24 months, especially in the intervention group. Consequently, at 24 months, between-group differences were small and did not reach significance. Yet, levels of body dissatisfaction and dysfunctional investment remained below initial values (for both groups). Results were similar for both body image dimensions. Structured PA (at 12 and 24 months) and lifestyle PA (at 24 months) were positively associated with (r > -0.25, P < 0.05) and partially mediated body image improvements, especially in the investment component (95% confidence interval of -1.88 to -0.27 for structured PA at 12 months, 95% confidence interval of -1.94 to -0.21 for lifestyle PA at 24 months). In general, change in evaluative body image was not mediated by exercise participation, seeming more dependent on weight change. CONCLUSIONS These findings highlight the importance of PA as a contributing factor in the improvement of body image in overweight/obese women, mainly by reducing excessive salience of appearance to ones life and self. Lifestyle PA may also be a valid option, particularly in the long term. Exercise might provide a buffer against body image deterioration overtime, favoring lasting weight loss maintenance.

Physical Wellness, Health Care, and Personal Autonomy

In this chapter, we review the self-determination theory perspective and current empirical evidence linking personal autonomy with physical well-being within and across cultures. Physical well-being consists of physical health and health-related behaviors (e.g., tobacco use, nutrition, physical activity, medication adherence). It is our thesis that a clear understanding of the relation between autonomy and physical well-being is relevant for all cultures. First, as SDT predicts, evidence suggests that higher levels of personal autonomy universally result in better physical well-being. Second, recent developments in biomedical ethics and informed decision making have elevated respect for patient autonomy to be an explicit, highest level goal of health care. Together the empirical evidence and these ethical mandates foretell an increasing emphasis on the role of personal autonomy in the delivery of health care. Accordingly, in the current review we examine the literature for studies that report the quantitative relations between different measures of personal autonomy and physical health, and autonomy and health-related behaviors. Most studies occur within single cultures, and find a consistent, positive relation between personal autonomy, or its change, and physical health. We discuss these findings and their limitations. We also suggest how future research can more fully establish and explore the causal linkages between personal autonomy and physical well-being.

Psychosocial Pretreatment Predictors of Weight Control: A Systematic Review Update

Objective: Systematically identifying pretreatment characteristics that predict successful weight management is important to improve intervention efficacy and clinical practice. This study provides a comprehensive update of a 2005 review on pretreatment predictors of successful weight management. Methods: Results of 37 recent original studies from peer-reviewed journals were merged with the results from the 2005 review. A critical appraisal of the 66 studies included was provided, and meta-analyses were performed when feasible. Results: Fewer previous weight loss attempts were the most consistent pretreatment predictor of successful weight management, although with a small effect size. Importantly, several variables were identified as non-significant predictors of weight loss, showing trivial effects (e.g., eating self-efficacy). Many psychosocial factors remain too little studied to allow reliable conclusions regarding their predictive value. Conclusion: Previous dieting attempts were identified as the soundest predictor of successful weight management. Several factors, previously considered barriers to successful weight management and now identified as non-predictors, require more investigation given the limitations identified in this review. Importantly, due to a comparably thin empirical basis for many predictors, further research is essential to move the field forward. Implications of the current state of research and necessary steps to improve intervention efficacy and clinical practice are discussed

Predictors of Successful Weight Control: Cross-cultural Moderators of Treatment Outcomes

Given the heterogeneity of effect sizes within the population for any treatment, identifying moderators of outcomes is critical [1]. In weight management programs, there is a high individual variability in terms of weight loss and an overall modest success [2]. Some people will adopt and sustain attitudes and behaviors associated with weight loss, while others won’t [3]. To predict weight loss outcome just from the subject’s baseline information would be very valuable [4,5]. It would allow to: