Does Motivational Interviewing Improve Behavioral Weight Loss Outcomes for Obesity? — BWLP+MI  

Obesity Clinical Trial

Official title: Adding Motivational Interviewing to a Behavioral Weight Loss Treatment for Obesity: A Randomized Controlled Trial

Status Completed

Clinical Trial Summary

The purpose of this study is to determine whether adding motivational interviewing (MI) to a behavioural weight loss program (BWLP) results in improved weight loss in adults with overweight and obesity.

Clinical Trial Description

Although behavioural weight loss programs (BWLP) are typically the first line of treatment for overweight and obesity, they are plagued by high attrition rates and poor adherence. Studies evaluating the benefit of adding motivational interviewing (MI) to BWLPs have yielded mixed findings. The main purpose of this randomized controlled trial was to assess the efficacy of adding MI to a BWLP on weight loss and adherence outcomes among 135 overweight and obese individuals who were enrolling in a 12-week BWLP.

This study used a randomized, controlled, longitudinal, between-subjects design to investigate the effects of a two-session MI intervention on weight loss in obese participants who enrolled in a behavioural weight loss program. Patients received either two 45-60 minute MI interventions or two 45-60 minute attention control interviews. The control group interview consisted of questions ascertaining weight history, diet history, dietary awareness and physical activity. Questions for the control group focused primarily on assessment of past behaviour whereas questions for the MI group focused on enhancing motivation by exploring and resolving ambivalence. Weight was measured at baseline, end of the BWLP, 1 month following BWLP completion, and 6 months following BWLP completion. Program adherence (measured as number of BWLP sessions attended out of 24) was assessed a the main secondary dependent measure. Importance, readiness, and confidence for weight change were also assessed throughout the study, along with several other secondary outcome measures.

Research personnel informed all BWLP participants about the study at the initial BWLP group intake assessments, which occurred just prior to the commencement of the formal BWLP. Individuals who expressed interest in participating were contacted by phone by a research assistant and screened for eligibility. If eligible, an appointment was made for the first MI/control session which was scheduled within the first two weeks of the BWLP. Participants were asked to complete the change rating questionnaires prior to this interview (i.e., importance, readiness, and confidence for change ratings), and randomization occurred immediately prior to this interview. After the first interview, participants were contacted during the 10th week of the BWLP to schedule a second MI/control session, which occurred approximately during the 12th week of the program. Immediately following each interview, all participants filled out the change rating questionnaires. Participants were all contacted several weeks following program completion to schedule the one-month follow-up assessment. Finally, all participants were contacted approximately five months following program completion in order to schedule the six-month follow-up assessment.

Sessions were tape recorded for all participants for quality assurance purposes. A subset of tapes were used to assess for treatment integrity. ;

Study Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind (Outcomes Assessor), Primary Purpose: Treatment

Related Conditions & MeSH terms

• Obesity
• Overweight
• Weight Loss

• NCT number: NCT02649634
• Study type: Interventional
• Source: University of Calgary
• Status: Completed
• Phase: N/A
• Start date: September 2007
• Completion date: January 2010