Impact of Group Size in Weight Loss Interventions

This study has been completed.
Information provided by (Responsible Party):
Florida State University Identifier:
First received: July 16, 2010
Last updated: March 4, 2015
Last verified: March 2015
The present study will assess whether the size of treatment groups (groups of 10 vs. 30 participants) affects short- and long-term weight loss. It is hypothesized that participants assigned to a small group will exhibit similar short-term and long-term weight losses (i.e., weight loss at months 6 and 12) as compared to those assigned to a large group.

Condition Intervention Phase
Weight Loss
Behavioral: behavioral weight loss program
Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: Improving Weight Loss Maintenance Through Alternatives Schedules of Treatment

Resource links provided by NLM:

Further study details as provided by Florida State University:

Primary Outcome Measures:
  • change in weight from baseline to month 12 [ Time Frame: 12 months ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • adherence to treatment protocol [ Time Frame: 12 months ] [ Designated as safety issue: No ]
    number and proportion of treatment sessions attended

Estimated Enrollment: 70
Study Start Date: July 2010
Study Completion Date: December 2014
Primary Completion Date: December 2014 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Small group
10-member groups
Behavioral: behavioral weight loss program
weekly, group-based lifestyle weight loss program
Active Comparator: Large group
30-member groups
Behavioral: behavioral weight loss program
weekly, group-based lifestyle weight loss program


Ages Eligible for Study:   21 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Adults (at least 21 years-old)
  • Health insurance coverage with Capital Health Plan (CHP)
  • Body mass index BMI between 30-45 kg/m2

Exclusion Criteria:

  • BMI is less than 30 kg/m2 or greater than 45 kg/m2
  • Weight loss > 10 pounds in past 6 months
  • Acute or chronic illnesses for which weight loss is contraindicated
  • Unwilling or unable to give informed consent
  • Unwilling to accept random assignment
  • Unwilling or unable to travel to CHP clinic for assessments and groups
  • Likely to relocate out of the area in the next 12 months
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Please refer to this study by its identifier: NCT01165151

United States, Florida
Florida State University
Tallahassee, Florida, United States, 32306
Sponsors and Collaborators
Florida State University
  More Information

Responsible Party: Florida State University Identifier: NCT01165151     History of Changes
Other Study ID Numbers: DK081607-01A1 
Study First Received: July 16, 2010
Last Updated: March 4, 2015
Health Authority: United States: Institutional Review Board

Keywords provided by Florida State University:
weight loss
group size

Additional relevant MeSH terms:
Body Weight
Weight Loss
Body Weight Changes
Signs and Symptoms processed this record on April 27, 2016