Physical Activity, Nutrition, and Obesity

E5 (Free Paper Session): Self-determination Theory

PREVIOUS WEIGHT LOSS ATTEMPTS: ASSOCIATIONS WITH SELF- DETERMINATION AND BODY IMAGE IN OVERWEIGHT AND OBESE WOMEN

Authors: Eliana Carraça- Faculty of Human Movement, Technical University of Lisbon, Marlene Silva - Faculty of Human Movement, Technical University of Lisbon , Paulo Vieira - Faculty of Human Movement, Technical University of Lisbon, Silvia Coutinho - Faculty of Human Movement, Technical University of Lisbon, Margarida Castro - Faculty of Human Movement, Technical University of Lisbon, Claudia Minderico - Faculty of Human Movement, Technical University of Lisbon, David Markland - School of Sport Health and Exercise Sciences, Bangor University, Pedro Teixeira - Faculty of Human Movement, Technical University of Lisbon

Purpose: In weight control programs, the number of previous weight loss attempts is a consistent negative moderator of success. We sought to analyze if, and by what mechanisms self-determination and body image predict previous dieting attempts, in overweight and obese women. Methods: Before starting obesity treatment, 255 women (37.5±7.1 yr; 31.6±4.1 kg/m2) completed a comprehensive body image psychosocial battery, the Self-Determination Scale (sub-scales: self-awareness, perceived choice) and a weight/dieting history questionnaire. Regression analysis, using Preacher and Hayes (2007) procedures to test indirect/mediated effects, were used for statistical analyses. Results: Previous weight loss attempts (WLA) were predicted by body shape concerns (BSC, r=0.34; p<0.001), r="-0.15;" p="0.035)," r="0.16;" p="0.021)," r="0.25;" r="-0.45;">

EXERCISE INTRINSIC MOTIVATION, AUTONOMOUS SELF-REGULATION, AND PSYCHOLOGICAL MOTIVES AS MEDIATORS OF PHYSICAL ACTIVITY DURING WEIGHT MANAGEMENT

Authors: Marlene Silva - Faculty of Human Movement, Pedro Teixeira - Faculty of Human Movement, Paulo Vieira - Faculty of Human Movement, Margarida Castro - Faculty of Human Movement, Claudia Minderico - Faculty of Human Movement, Silvia Coutinho - Faculty of Human Movement, Antonio Palmeira - Universidade Lusofona de Humanidades e Tecnologias, David Markland - Bangor University

Purpose: To analyse the role of exercise intrinsic motivation (IM), locus of causality (LC), autonomous self-regulation (ASR), and psychological motives (PM) as mediators of physical activity (PA) during an obesity treatment program based on Self-Determination Theory (SDT). Methods: 255 women (37.5±7.1y; 31.6±4.2kg/m2) participated and were assigned to intervention/control groups. The intervention (30 weekly sessions) was specifically designed to increase PA, following SDT principles. Controls received a general health education program. Assessments included putative SDT mediators and PA: walking, moderate + vigorous PA (7-day PAR), and lifestyle PA. Multiple regression was used to test for mediation, as forwarded by Baron and Kenny. Indirect/mediated effects were tested using procedures described by Preacher and Hayes (2007). Results: The intervention significantly changed all putative SDT mediators (p<0.001) p="0.017).">

SUCCESSFUL APPLICATION OF SELF-DETERMINATION THEORY TO BEHAVIORAL WEIGHT MANAGEMENT: RESULTS FROM A RANDOMIZED CONTROLLED TRIAL IN WOMEN

Authors: Pedro J. Teixeira - Faculty of Human Movement, Marlene N. Silva - Faculty of Human Movement, Paulo N. Vieira - Faculty of Human Movement, Claudia S. Minderico - Faculty of Human Movement, Margarida M. Castro - Faculty of Human Movement, Silvia Coutinho - Faculty of Human Movement, Teresa Santos - Faculty of Human Movement, Luis B Sardinha - Faculty of Human Movement

Purpose: To describe a weight management program for overweight/obese women centered on physical activity (PA) and based on Self-Determination Theory, and report results for key intervention outcomes. Method: 255 women (37.5±7.1y; 31.6±4.1kg/m2) were randomized into intervention/control groups. The program included 30 weekly/bi-weekly group meetings; autonomous motivation and a more internal PA/diet behavioral regulation were targeted. The autonomy-supportive treatment climate was hypothesized to enhance self-determination, perceived competence, and intrinsic motivation for PA, aiming for lasting behavioral/weight changes. Physical activity (7-day PAR, Ob-PAR) and weight were assessed at baseline and 12 months (83.2% retention). Mediation analysis was tested with multiple regression and indirect effects estimated with the Preacher and Hayes procedure. Results: Intervention-control differences for 12-month changes were: +94±28 min/wk for moderate + vigorous PA, +108±34 min/wk for walking, ES=0.88 for a lifestyle PA index, and -5.0±0.8% for body weight (p<0.003 p="0.002)," r="-0.33," r="-0.15," p="0.032)," r="-0.25," p="0.001)" p="0.005">

ANALYSIS OF RECIPROCAL EFFECTS BETWEEN CHANGES IN WEIGHT AND BODY IMAGE IN A BEHAVIORAL WEIGHT LOSS TREATMENT

Authors: Antonio L. Palmeira - Universidade Lusofona de Humanidades e Tecnologias, Pedro J. Teixeira - Faculty of Human Movement, Technical University of Lisbon, Marlene N Silva - Faculty of Human Movement, Technical University of Lisbon, David A. Markland - Bangor University, Teresa L. Branco - Faculty of Human Movement, Technical University of Lisbon, Sandra Martins - Faculty of Human Movement, Technical University of Lisbon, Claudia Minderico - Faculty of Human Movement, Technical University of Lisbon, Luis B. Sardinha - Faculty of Human Movement, Technical University of Lisbon

Purpose: To analyse the reciprocity between changes in weight and changes in body shape concerns (BSC), analyzed alternatively as a mediator and an outcome, during a behavioral obesity treatment program in women. Methods: Subjects (BMI=31.1±4.1 kg/m2; Age=38.4±6.7 y) were 144 women who attended a 12-month obesity treatment program and a comparison group (n=49), who received a general health education program. Weight, BSC and exercise level were assessed at baseline and 12-months. Multiple mediation was tested by multiple regression, analyzing total/direct/indirect effects of each variable, while controlling for other mediators (see Preacher & Hayes, 2007). Treatment/comparison was the independent variable, exercise was analyzed as a mediator, while changes in weight and BSC were analyzed alternatively as mediators and dependent variables. Results: Weight loss was greater in the treatment group (-5.6±6.8% vs. 1.2±4.6%, p<.001). Both groups improved their body image (p<.001) and the intervention group was more active at treatment's end (p<.001). The BSC mediation model explained 24% of weight change (p<.001). Total, direct, and total indirect effects were significant, suggesting that changes in BSC partially mediated treatment effects on weight. The weight change mediation model explained 17% of treatment-induced change in BSC (p<.001). The specific indirect effects showed that weight change completely mediated change in body image. Exercise was not a mediator in either model. Conclusion: The reciprocal effects hypothesis was confirmed; changes in weight and body image appear to influence each other during the course treatment, adjusting for physical activity. The strongest effect was observed for weight as a mediator of changes in concerns with body shape and feelings of being too fat.

A Sessions: Symposia
A1: The Scale Is The Limit? Weighing Obesity Interventions from an Ethical Perspective. Chair: Sofie Vandamme, Department of Medical Ethics and Philosophy, Erasmus MC, Rotterdam, The Netherlands

“You Should Lose Weight!”: A Note Of (Evidence-Based) Caution Before You Say These Words

Authors: Teixeira, Pedro

Abstract: Purpose: For those involved in treatment obesity, such as behavioral/lifestyle therapies, facing questions with ethical implications is common. This presentation will identify critical decisions to be made before/during treatment, highlight relevant research findings, and provide ethically-sound recommendations. Methods: Empirical and theoretical support for this presentation comes from the author's clinical/practical experience and from key/representative studies available in the obesity literature. Results: Recommending that someone loses weight (and advising on how to do it) generally assumes the expert/provider to be sufficiently certain about the following aspects, among others: i) When is body weight/fat more likely to impair physical health? The weight-morbidity association is strong only at the highest obesity levels, and effect-moderators (e.g., physical activity) exist and must be considered; ii) How much weight loss can realistically be "promised"? The best studies show... not a lot (beyond 5%)! However, predictor studies provide some guidance on maximizing (and/or anticipating) individual success level; iii) How to deal with very high weight loss goals? Evidence suggests more intrinsic motivations and moderate expectations may pay off; iv) What is the most effective treatment? The one that succeeds in increasing physical activity adherence; v) How long should treatment last? According to the (limited) evidence, the longer the better; but alternatives to continuous care should be sought; vi) Are there risks of weight loss? They can be minimized and do not outweigh benefits. Conclusion: Only by adequately addressing these (and other) questions can the provider intervene more ethically: disclose all relevant information, provide choice, not cause harm, effectively allocate limited resources, keep the patient's best interest (and dignity) in mind, and support his/her autonomy.

B1: It’s About Time: Modeling Real-Time Assessment Data on Physical Activity and Nutrition.

Chair: Jutta Mata, Faculty of Human Movement – Technical University of Lisbon, Lisbon, Portugal & Max Planck Institute for Human Development, Berlin, Germany; Mark Pereira, University of Minnesota, Minneapolis, MN, USA

Using Ecological Momentary Assessment To Understand The Role Of Psychosocial And Environment Factors In Weight Control

Authors: Mata, Jutta; Santos, Teresa; Vieira, Paulo N. ; Silva, Marlene N.; Coutinho, Silvia; Teixeira, Pedro J.

Abstract: Purpose: The determinants of successful weight loss in previously overweight people are not fully understood. This study uses a process-oriented instrument, Ecological Momentary Assessment (EMA), which measures behaviors, states, and ecological influences on a daily level to 1) investigate how daily fluctuations in exposure to environments facilitating physical activity (PA) and healthy nutrition are related to fluctuations in behavior-specific self-efficacy and 2) compare differences in day-to-day self-efficacy in participants with high versus low weight loss. Methods Over two 2-week periods during a behavioral weight control program, 47 overweight women filled out questions on psychosocial variables (including self-efficacy) related to PA, nutrition, situational, and ecological factors on a daily level. Coefficients of variation were used to study associations between intra-individual fluctuation in PA- and nutrition-related self-efficacy and environments facilitating these behaviors. Differences in self-efficacy between participants with high and low 4-month weight loss were determined using Multilevel Modeling. Results: Daily fluctuations in behavior-specific self-efficacy were significantly correlated with exposure to environments facilitating them (r(PA)=.51, r(nutrition)=.26, p<.001). Multilevel models showed that nutrition self-efficacy over two weeks was higher in people with high weight loss (p<.05). However, there was no difference between the groups in PA-related self-efficacy (p=.81). Conclusions: This study highlights two methods that can be used to analyze EMA data. Results provide insight into the process underlying associations between exposure to specific environments and fluctuations in psychosocial factors, and the importance of daily-level nutrition self-efficacy for initial weight loss success.