Objective: To evaluate the effectiveness of teledietetics in weight loss for 24 weeks and the cost-effectiveness of weight loss between face-to-face and teledietetics services. Study setting: The study was conducted at a community health center and a community dietetics clinic. Study design: The study was a quasiexperimental design. Methods: Fifty adults aged 20–50 with a BMI ≥23 participated in the study. The face-to-face (FD) group received 12 dietary counselling sessions and recorded their diet in a log book. The teledietetics (TD) group attended three group nutrition seminars and recorded their diet on a Web-based platform. Changes in variables were compared using an independent t-test. Direct and indirect costs were applied to compute cost-effectiveness ratios. Results: At week 6, the FD group showed greater reductions in all variables than did the TD group. At week 12, the effects reversed. At week 24, the accumulated reductions in weight and fat in the TD group were significantly higher than those in the FD group (all at p < 0.0001). The observed direct costs for 1% weight loss and 1% fat loss were USD 28.24 and USD17.09, respectively. Conclusion: A dietetic service delivered as a teledietetics model is more cost-effective than the face-to-face dietetics model in weight reduction. Copyright © 2015 The Author(s).