The purpose of this study is to carry out a field trial to evaluate the effectiveness of the b-SLIM digital Super Coach in a convenient sample of overweight and obese adults. The effectiveness will be evaluated at the individual level by means of a randomized trial. By combining or not combining the use of the b-SLIM digital Super Coach with a conventional physical activity and nutrition coaching, the effectiveness of the Super Coach of the (user-driven) 'Super Coach' compared to a conventional face to face weight loss program can be determined. Outcomes will be measured at the level of health behavior (i.e., physical activity and nutrition), body composition, physical fitness, psychosocial factors (e.g., motivation) and program adherence. The field trial will take place in Leuven (Belgium).