[show abstract][hide abstract] ABSTRACT: The scope of this article is to describe the Portuguese Weight Control Registry (PWCR) methodology and the participants currently enrolled specifically with respect to their individual and family weight history, previous weight loss attempts, and psychosocial characteristics. One hundred and ninety-eight adults (age: 39.7±11.1 years; BMI: 26.0±3.9 kg/m2), 59% women, filled out a questionnaire about demographics, health-related behaviors and motivation, and methods and strategies used to lose and/or maintain weight loss. Participants reported an average weight loss of 17.4 kg for an average of 29 months. Concerning the number of weight loss attempts, 73% of participants reported a maximum of three attempts of going on a diet, and 34% indicated only one attempt to lose weight in the past. The PWCR now features a considerable number of successful long-term weight loss maintainers in Portugal. Participants will be followed over the next years to learn about their characteristics and weight loss strategies in further detail, as well as to identify predictors of continued weight loss maintenance.
[show abstract][hide abstract] ABSTRACT: The purpose of this study was to evaluate health-related quality of life and other psychosocial characteristics, including eating self-regulation and body image, in a group of successful long-term weight loss maintainers. Women enrolled in the Portuguese Weight Control Registry (n = 107) were matched and compared to women at the end of a behavior weight loss treatment program (n = 107), and also with women in the community who were not trying to lose weight (n = 107). Successful maintainers displayed higher quality of life and a more positive profile in selected eating and exercise markers of self-regulation compared to similarly-weighed women not attempting weight loss, but not when compared to the 'weight loss treatment' group. However, results also suggest that concerns with body shape and size may persist after weight loss and that some aspects of well-being and eating self-regulation can be more successfully targeted in specific weight loss programs.
Journal of Behavioral Medicine 09/2012; · 3.10 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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).
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.
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.
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 one's 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.
Medicine and science in sports and exercise 02/2012; 44(8):1604-12. · 3.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
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 intervention's 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.
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).
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.
Medicine and science in sports and exercise 04/2011; 43(4):728-37. · 3.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this study, we investigated the associations between body image and psychological well-being, exploring the mediating role of controlled regulation for entering obesity treatment. In addition, we analyzed whether investment body image was more strongly associated with controlled regulation (and subsequent well-being)
compared to evaluative body image. These analyses were performed controlling for baseline BMI effects. Participants were 139 overweight women (age: 38.0 ± 6.7 year; BMI: 32.0 ± 4.1 kg/m2) entering treatment. Evaluative and investment body image, controlled regulation, and psychological well-being were assessed. Body image investment was positively associated with controlled regulation; evaluative body image was not. Controlled regulation was negatively associated with self-esteem and psychological functioning. Controlled regulation partially mediated the effects of body image investment on self-esteem, but did not mediate its effects on psychological functioning. Results suggest that dysfunctional body image investment might undermine well-being within overweight women, partly by increasing controlled regulation for entering obesity treatment. Discussion focuses on the importance of enhancing body image and autonomy during treatment to improve well-being and weight outcomes.
Motivation and Emotion 01/2011; 35:423-434. · 1.55 Impact Factor
[show abstract][hide abstract] ABSTRACT: This study examined the association of autonomy-related variables, including exercise motivation, with psychological well-being and quality of life, during obesity treatment. Middle-aged overweight/obese women (n = 239) participated in a 1-year behavioral program and completed questionnaires measuring need support, general self-determination, and exercise and treatment motivation. General and obesity-specific health-related quality of life (HRQOL), self-esteem, depression, and anxiety were also assessed. Results showed positive correlations of self-determination and perceived need support with HRQOL and self-esteem, and negative associations with depression and anxiety (P < .001). Treatment autonomous motivation correlated positively with physical (P = .004) and weight-related HRQOL (P < .001), and negatively with depression (P = .025) and anxiety (P = .001). Exercise autonomous motivation was positively correlated with physical HRQOL (P < .001), mental HRQOL (P = .003), weight-related HRQOL (P < .001), and self-esteem (P = .003), and negatively with anxiety (P = .016). Findings confirm that self-determination theory's predictions apply to this population and setting, showing that self-determination, perceived need support, and autonomous self-regulation positively predict HRQOL and psychological well-being.
[show abstract][hide abstract] ABSTRACT: This study tested whether different forms of physical activity (PA) were associated with eating self-regulation during weight control, and if changes in eating behavior mediated the relationship between PA and weight loss, in overweight/obese women.
239 women (37.6+/-7.0 years; 31.3+/-4.1kg/m(2)) participated. The intervention group received a 12-month group behavioral treatment designed to increase autonomy and self-regulation for weight control. Controls received a health education program. Assessments included body weight, structured and lifestyle exercise/PA, and eating self-regulation.
Moderate+vigorous and lifestyle PA were associated with 12-month change in most eating variables (p<0.05) and with body weight change (p<0.01). Mediation analysis showed that flexible cognitive restraint and emotional eating fully mediated the relation between lifestyle PA and weight change (effect ratio: 0.63). About 34% of the effect of moderate+vigorous PA on weight change was explained by these same mediators (partial mediation).
Exercise and PA may positively influence weight control through eating self-regulation. Flexible dietary control and reduced emotional overeating are mechanisms by which an active lifestyle can contribute to long-term weight management.
Regular exercise and PA can contribute to improved eating behaviors during weight management. This could represent an important incentive for people seeking weight control.
Patient Education and Counseling 02/2010; 79(3):320-6. · 2.37 Impact Factor
[show abstract][hide abstract] ABSTRACT: ObjectivesThis study analyzed mechanisms by which a one-year obesity treatment intervention based on self-determination theory (SDT) influenced physical activity level and whether motivational predictors differed for structured vs. lifestyle forms of physical activity.DesignRandomized controlled trial lasting 1-year.MethodPre-menopausal overweight and obese women (n = 239; 37.6 ± 7.1 y; 31.5 ± 4.1 kg/m2) participated in a group intervention designed to increase physical activity and motivation, following SDT. Partial least squares (PLS) latent variable modeling was used to test a cross-sectional multiple-level mediation model comprising experimentally-manipulated contextual need support, perceived need satisfaction, and motivational regulations for two distinct forms of physical activity.ResultsThe structural model explained a large amount of variance (62%) for intrinsic motivation, and moderate amounts of variance (16–25%) for the remaining regulations and exercise behaviors. Moderate and vigorous exercise was positively influenced by intrinsic motivation (p < .001) whereas lifestyle physical activity was not significantly predicted by motivational regulations. Behavioral regulations were influenced by perceived autonomy and perceived competence and both needs were affected by contextual support from treatment climate (p < .001).ConclusionsResults provide support for using the SDT framework to understand physical activity motivational processes in the context of weight management. Results also highlight structured and lifestyle physical activity as being promoted by different processes as a result of the intervention: more direct effects on lifestyle physical activity and indirect effects on structured exercise, mediated by intrinsic motivation.
Psychology of Sport and Exercise 01/2010; · 1.72 Impact Factor
[show abstract][hide abstract] ABSTRACT: Behavior change interventions are effective to the extent that they affect appropriately-measured outcomes, especially in experimental controlled trials. The primary goal of this study was to analyze the impact of a 1-year weight management intervention based on self-determination theory (SDT) on theory-based psychosocial mediators, physical activity/exercise, and body weight and composition. Participants were 239 women (37.6 +/- 7.1 years; 31.5 +/- 4.1 kg/m(2)) who received either an intervention focused on promoting autonomous forms of exercise regulation and intrinsic motivation, or a general health education program (controls). At 12 months, the intervention group showed increased weight loss (-7.29%,) and higher levels of physical activity/exercise (+138 +/- 26 min/day of moderate plus vigorous exercise; +2,049 +/- 571 steps/day), compared to controls (P < 0.001). Main intervention targets such as more autonomous self-regulation (for treatment and for exercise) and a more autonomous perceived treatment climate revealed large effect sizes (between 0.80 and .96), favoring intervention (P < 0.001). Results suggest that interventions grounded in SDT can be successfully implemented in the context of weight management, enhancing the internalization of more autonomous forms of behavioral regulation, and facilitating exercise adherence, while producing clinically-significant weight reduction, when compared to a control condition. Findings are fully consistent with previous studies conducted within this theoretical framework in other areas of health behavior change.
Journal of Behavioral Medicine 12/2009; 33(2):110-22. · 3.10 Impact Factor
[show abstract][hide abstract] ABSTRACT: Successful weight management relies on at least two health behaviors, eating and exercise. However, little is known about their interaction on a motivational and behavioral level. Based on the Hierarchical Model of Motivation the authors examined whether exercise-specific motivation can transfer to eating regulation during a lifestyle weight control program. The authors further investigated whether general, treatment-related, and exercise motivation underlie the relation between increased exercise and improved eating regulation.
Overweight/obese women participated in a 1-year randomized controlled trial (N = 239). The intervention focused on promoting physical activity and internal motivation for exercise and weight loss, following Self-Determination Theory. The control group received general health education.
General and exercise specific self-determination, eating self-regulation variables, and physical activity behavior.
General self-determination and more autonomous exercise motivation predicted eating self-regulation over 12 months. Additionally, general and exercise self-determination fully mediated the relation between physical activity and eating self-regulation.
Increased general self-determination and exercise motivation seem to facilitate improvements in eating self-regulation during weight control in women. These motivational mechanisms also underlie the relationship between improvements in exercise behavior and eating regulation.
Health Psychology 11/2009; 28(6):709-16. · 3.83 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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/m(2)) 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 (R(2) = 0.31, P < 0.001; effect ratio: 0.37), but only flexible restraint and exercise self-efficacy mediated 24-month weight loss (R(2) = 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.
[show abstract][hide abstract] ABSTRACT: Research on the motivational model proposed by Self-Determination Theory (SDT) provides theoretically sound insights into reasons why people adopt and maintain exercise and other health behaviors, and allows for a meaningful analysis of the motivational processes involved in behavioral self-regulation. Although obesity is notoriously difficult to reverse and its recidivism is high, adopting and maintaining a physically active lifestyle is arguably the most effective strategy to counteract it in the long-term. The purposes of this study are twofold: i) to describe a 3-year randomized controlled trial (RCT) aimed at testing a novel obesity treatment program based on SDT, and ii) to present the rationale behind SDT's utility in facilitating and explaining health behavior change, especially physical activity/exercise, during obesity treatment.
Study design, recruitment, inclusion criteria, measurements, and a detailed description of the intervention (general format, goals for the participants, intervention curriculum, and main SDT strategies) are presented. The intervention consists of a 1-year group behavioral program for overweight and moderately obese women, aged 25 to 50 (and pre-menopausal), recruited from the community at large through media advertisement. Participants in the intervention group meet weekly or bi-weekly with a multidisciplinary intervention team (30 2 h sessions in total), and go through a program covering most topics considered critical for successful weight control. These topics and especially their delivery were adapted to comply with SDT and Motivational Interviewing guidelines. Comparison group receive a general health education curriculum. After the program, all subjects are follow-up for a period of 2 years.
Results from this RCT will contribute to a better understanding of how motivational characteristics, particularly those related to physical activity/exercise behavioral self-regulation, influence treatment success, while exploring the utility of Self-Determination Theory for promoting health behavior change in the context of obesity.
Clinical Trials Gov. Identifier NCT00513084.
BMC Public Health 08/2008; 8:234. · 2.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: The aim of this work is to compare participant characteristics and weight loss and weight loss maintenance strategies adopted by an initial cohort of the Portuguese Weight Control Registry (PWCR) with published results from the National Weight Control Registry's (NWCR).Sample includes 198 adults (age: 39.7 ± 11.1 yr; BMI: 26.0 ± 3.9 kg/m2), 59% women, who voluntarily registered to the PWCR and completed one initial questionnaire including demographics, methods and strategies used to lose weight and/or to maintain weight, and a laboratory assessment. Individuals meeting inclusion criteria reported a weight loss of 17.4 kg, maintained for an average of 29 months. The PWCR sample is younger, heavier, and more gender-balanced than the NWCR sample.Modifying both dietary intake and physical activity (PA) levels was the most common weight loss strategy in Portuguese individuals (82%), while 89% reported it in NWCR. To lose weight, 43% of all PWCR participants started to use stairs, 91% started to eat breakfast every day, 79% chose “better foods”, 74% reported “limiting food quantities”, and 86% frequently limit fat intake. To keep weight loss, PWCR individuals engaged weekly in 250 minutes of moderate and vigorous physical activity and a weekly physical activity energy expenditure of 3422 kcal (NWCR: 2621 kcal). Other strategies were used: 69% chose “better foods” (NWCR: 92%), 87% frequently limiting fat intake (NWCR: 38%), 63% reported “limiting food quantities” (NWCR: 49%), 98% ate breakfast every day (NWCR: 78%), and 65% weighed themselves at least once a week (NWCR: 75%).Data from the first PWCR cohort show similarities with the larger US sample of successful maintainers but also some differences. This work discusses these differences.
Revista Portuguesa de Saúde Pública. 30(2):115–124.
[show abstract][hide abstract] ABSTRACT: Objective: Successful weight management relies on at least two health behaviors, eating and exercise. However, little is known about their interaction on a motivational and behavioral level. Based on the Hierarchical Model of Motivation the authors examined whether exercise-specific motivation can transfer to eating regulation during a lifestyle weight control program. The authors further investigated whether general, treatment-related, and exercise motivation underlie the relation between increased exercise and improved eating regulation. Design: Overweight/obese women participated in a 1-year randomized controlled trial (N = 239). The intervention focused on promoting physical activity and internal motivation for exercise and weight loss, following Self-Determination Theory. The control group received general health education. Main Outcome Measures: General and exercise specific self-determination, eating self-regulation variables, and physical activity behavior. Results: General self-determination and more autonomous exercise motivation predicted eating self-regulation over 12 months. Additionally, general and exercise self-determination fully mediated the relation between physical activity and eating self-regulation. Conclusion: Increased general self-determination and exercise motivation seem to facilitate improvements in eating self-regulation during weight control in women. These motivational mechanisms also underlie the relationship between improvements in exercise behavior and eating regulation.