Multiple factors influence long-term weight-loss success, as shown by the National Weight Control Registry. We evaluated the influence of two of those factors, diet instruction by a registered dietitian (RD) and frequency of weigh-in visits, on initial weight-loss success. Twenty-six overweight subjects with a baseline body mass index of 33.2±3.7 and a mean age of 43±12 years were enrolled in a weight-loss study. The 11-week weight loss period included 33 total visits, with weekly RD-instructed classes with a weigh-in, and 22 semiweekly related weigh-in visits without an RD present. Classes covered topics in the areas of energy restriction, dietary change, exercise, and behavior modification. Subjects were enrolled at different time points within the class topic rotation but all completed the 11-week program. The mean weight loss for all subjects was 3.8±2.8 kg (P<0.001). Weight loss (%) was significantly correlated with attendance of RD-instructed classes (r=0.451, P=0.021) but not attendance at weigh-ins that did not include RD-instructed classes (r=0.329, P=0.101). We conclude that RD-led dietary instruction was more beneficial than frequent weigh-in visits alone in promoting weight loss.