Background: Previous studies incorporating Motivational Interviewing administered via Co-Active Life Coaching tools (MI-via-CALC) have elicited positive results among adults with obesity. However, there is a paucity of this research that includes sufficient power and a comparison group. This study's purpose was to compare MI-via-CALC with a validated obesity intervention among university students. Methods: Participants (n = 45) were randomised to either a telephone-based 12-week: (a) MI-via-CALC program whereby a certified coach worked with subjects to achieve goals through dialogue; or (b) lifestyle modification treatment following the LEARN Program for Weight Management. Participants completed the Rosenberg Self-Esteem Scale and Short Form Functional Health Status Scale (SF-36) at baseline, mid-, and post-treatment, and 3 and 6 months following the program. Results: Analyses revealed that both conditions elicited significant time effects between baseline and 6 months for self-esteem and all dimensions of the SF-36 (e.g. overall health). Conclusions: MI-via-CALC compares favorably with LEARN as an obesity treatment. Given that self-esteem and quality of life are essential for promoting behavior change among individuals with obesity, this study offers unique insights into their change processes. Future research should provide both treatments and allow participants to choose based on their personal preferences, learning styles, and needs.