Studies incorporating Motivational Interviewing via Co-Active life coaching (MI-via-CALC) have elicited positive results among obese adults; however there is a paucity of comprehensive MI-via-CALC-obesity research that includes sufficient statistical power and a validated comparison group. The purpose of this study was to compare two telephone-based interventions for obesity. University students were randomized to either a 12-week: (a) personalized MI-via-CALC program whereby a coach worked with participants to achieve goals; or (b) prescriptive education-based lifestyle treatment following the LEARN Program. This paper contains a detailed methodological account of the study with a view to informing the development of prospective coaching-based programs.