Purpose: The purpose of this study was to assess the impact of Co-active coaching on obese female university students’ body mass index (BMI), waist circumference (WC), functional health status and self-esteem, and conjointly to identify the coaching skills and primary agenda topics that facilitate coaching’s efficacy as an intervention for obesity.

Design: A multiple-baseline, single-subject research design was utilized.Methods: Two certified coaches provided an average of nine, 35-minute, one-on-one sessions with five students whose BMI?30kg/m2 (obesity threshold). Measures included BMI, WC, the Short-Form 36 (SF-36) Health Survey, and the Rosenberg Self-Esteem Scale. Visual inspection was used to analyze changes in BMI and WC. Statistical interpretations, supplemented with qualitative information from postintervention interviews, were used to determine whether a clinically significant difference in health status and/or self-esteem was achieved. Inductive content analysis was conducted on the interview transcripts and on 50 per cent of each participant’s coaching session transcripts.

Results: Visual inspection revealed no change in BMI for three, a decrease for one, and a slight increase for one participant. WC decreased for three participants and remained stable for two. Collectively, the effect sizes and qualitative statements indicated clinically significant improvements in participants’ self-esteem and physical, mental, and overall health statuses upon completion of the intervention. Powerful questions and acknowledgements were the most frequently used coaching skills.

Conclusions: Coaching and particular coaching skills were associated with a trend towards a decrease in WC and clinically significant increases in participants’ self-esteem and their mental, physical, and overall health statuses.