title: Time-based physical activity interventions for weight loss: a randomized trial.
abstract: OBJECTIVE
  This study aims to examine whether enhancing standard behavioral weight loss interventions (standard behavioral weight loss program (SBWP)) with additional strategies at the initiation of intervention (ADOPT) or providing the additional strategies at predetermined times over the intervention period (MAINTAIN) enhances 18-month weight loss.
  
  
  METHODS
  This was a clinical trial of participants (N = 195; mean ± SEM: age, 43.2 ± 8.6 yr; body mass index, 33.0 ± 3.4 kg·m) randomized to SBWP, ADOPT, or MAINTAIN. All participants were prescribed an energy-restricted diet and physical activity, with group intervention sessions delivered over 18 months. ADOPT participants received additional phone contact (months 1-3), supervised exercise (months 1-6), and behavior campaigns (months 4-9). MAINTAIN participants received additional phone contact (months 4-6), supervised exercise (months 7-12), and behavior campaigns (months 13-18).
  
  
  RESULTS
  There was a significant group-time interaction for weight loss (P = 0.0032). SBWP participants lost 9.3 ± 0.9, 7.8 ± 1.1, and 5.9 ± 1.2 kg at 6, 12, and 18 months, respectively. ADOPT participants lost 8.9 ± 0.9, 7.6 ± 1.2, and 5.8 ± 1.2 kg, whereas MAINTAIN participants lost 9.7 ± 0.9, 11.0 ± 1.2, and 9.0 ± 1.2 kg at 6, 12, and 18 months, respectively. The group-time interactions for SBWP versus MAINTAIN (P = 0.0033) and for ADOPT versus MAINTAIN (P = 0.0075) were significant. There was a significant group-time interaction for change in fitness (P = 0.0060). The group-time interaction for MAINTAIN versus ADOPT (P = 0.0018) was significant, with a trend for MAINTAIN versus SBWP (P = 0.0525).
  
  
  CONCLUSIONS
  MAINTAIN improves 18-month weight loss compared with SBWP and ADOPT, with statistical trends indicating that MAINTAIN results in greater improvements in fitness. These results suggest that time-based strategies emphasizing physical activity confer greater benefits when delivered later and over the full course of intervention. This provides valuable information for the implementation of time-based strategies for improving long-term weight loss and fitness in overweight and obese adults.
authors.affiliation: 1Department of Health and Physical Activity, Physical Activity and Weight Management Research Center, University of Pittsburgh, Pittsburgh, PA; 2Division of Public Health Sciences, Department of Biostatistical Sciences, Wake Forest University, Winston-Salem, NC; and 3Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: John M
authors.initials: JM
authors.lastname: Jakicic
authors.forename: Amy D
authors.initials: AD
authors.lastname: Rickman
authors.forename: Wei
authors.initials: W
authors.lastname: Lang
authors.forename: Kelliann K
authors.initials: KK
authors.lastname: Davis
authors.forename: Bethany Barone
authors.initials: BB
authors.lastname: Gibbs
authors.forename: Rebecca
authors.initials: R
authors.lastname: Neiberg
authors.forename: Marsha D
authors.initials: MD
authors.lastname: Marcus
mesh_terms: D000328:Adult; D001823:Body Composition; D050218:Body Fat Distribution; D002320:Cardiovascular Physiological Phenomena; D004038:Diet, Reducing; D005081:Exercise Therapy / Q000379:methods*; D005247:Feeding Behavior; D006801:Humans; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy / Q000628:therapy*; D010809:Physical Fitness; D012143:Respiratory Physiological Phenomena; D013997:Time Factors; D015431:Weight Loss; D061217:Weight Reduction Programs