Overweight and obesity are major public health problems associated with increased morbidity and mortality. Motivational interviewing is a patient-centered counseling approach that may improve lifestyle behaviors and weight management. This randomized controlled trial aims to evaluate the effect of motivational interviewing on anthropometric measurements, eHealth literacy, and healthy eating attitudes among overweight and obese adults attending Healthy Life Centers in Sakarya, Türkiye. Participants will be randomly assigned to either a motivational interviewing intervention group or a routine nutrition counseling control group. Outcomes will be assessed at baseline and after the intervention.