title: A randomized controlled trial to evaluate self-determination theory for exercise adherence and weight control: rationale and intervention description.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  Clinical Trials Gov. Identifier NCT00513084.
authors.affiliation: Department of Exercise and Health, Faculty of Human Kinetics, Technical University of Lisbon, Portugal. mnsilva@fmh.utl.pt
authors.forename: Marlene N
authors.initials: MN
authors.lastname: Silva
authors.forename: David
authors.initials: D
authors.lastname: Markland
authors.forename: Cláudia S
authors.initials: CS
authors.lastname: Minderico
authors.forename: Paulo N
authors.initials: PN
authors.lastname: Vieira
authors.forename: Margarida M
authors.initials: MM
authors.lastname: Castro
authors.forename: Sílvia R
authors.initials: SR
authors.lastname: Coutinho
authors.forename: Teresa C
authors.initials: TC
authors.lastname: Santos
authors.forename: Margarida G
authors.initials: MG
authors.lastname: Matos
authors.forename: Luís B
authors.initials: LB
authors.lastname: Sardinha
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Teixeira
mesh_terms: D000328:Adult; D015444:Exercise / Q000523:psychology*; D005260:Female; D015438:Health Behavior; D007722:Health Knowledge, Attitudes, Practice; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D008019:Life Style; D008875:Middle Aged; D009042:Motivation; D009765:Obesity / Q000523:psychology / Q000628:therapy; D050177:Overweight / Q000523:psychology / Q000628:therapy*; D026684:Personal Autonomy; D011582:Psychological Theory