Evidence indicates that attentional bias and dieter’s eating styles (i.e., external, emotional, restraint) play important roles in the success or failure of dieters. First, we studied food-related attentional bias (FAB; based on interference scores on a modified Stroop test), eating styles (Dutch Eating Behavior Questionnaire), and increases in body mass index (BMI) in overweight or obese dieters (n = 34) and nondieters (n = 35). Compared with nondieters, dieters showed higher FAB, which was positively associated with BMI. In addition, the majority of overweight and obese participants had higher scores on emotional and restrained eating styles. Second, we investigated the effect of a Food Attention Control Training Program (Food-ACTP) on reducing FAB and dieting success. Dieters (n = 49) were divided into three groups: intervention (training), no-intervention (control), and sham-intervention, all of whom were measured at pretest, posttest, and follow up. Only the intervention group showed reductions in their FAB, diet failure rate, and BMI at follow up. For the intervention group, there was a significant interaction between changes in FAB and eating styles in predicting decreases in BMI. Overall, this work shows that attentional bias plays an important role in eating behavior, and dieters can benefit from practicing with Food-ACTP as a complimentary intervention. The exact mechanism through which Food-ACTP improves dieting success awaits further investigation.