Comparison of the Effectiveness of Rumination-Focused Cognitive Behavioral Therapy and Classical Cognitive Behavioral Therapy on Depression, Anxiety, and Disordered Eating in Individuals with Obesity: A Single-Case Multiple-Baseline Study

Abstract

This study aimed to compare the effectiveness of rumination-focused cognitive behavioral therapy (RFCBT) and classical cognitive behavioral therapy (CBT) in reducing depression, anxiety, and disordered eating among individuals with obesity. A single-case experimental design with multiple baselines across participants was employed. Six adults aged 18–50 years with obesity were assigned to two three-participant treatment conditions: classical CBT and RFCBT. Baseline phases were staggered across four to six measurement points, followed by eight intervention assessments and four follow-up assessments. Both interventions were delivered in 10 weekly 60-minute sessions. Depression was assessed using the Beck Depression Inventory-II, anxiety using the Beck Anxiety Inventory, and disordered eating using the 12-item Eating Disorder Examination Questionnaire–Short Form. Data were analyzed through visual analysis and quantitative single-case indices, including Nonoverlap of All Pairs (NAP) and Tau-U. For baseline-to-intervention comparisons, NAP values for depression were 0.980 for classical CBT and 0.897 for RFCBT, while corresponding Tau-U values were 0.959 and 0.794. For anxiety, NAP values were 0.988 and 0.931 and Tau-U values were 0.865 and 0.751, respectively. For disordered eating, NAP values were 0.812 and 0.758, with Tau-U values of 0.624 and 0.516. In baseline-to-follow-up comparisons, NAP values reached 1.000 for depression, anxiety, and disordered eating in both treatment conditions. Tau-U reached 1.000 for depression and disordered eating in both conditions and 0.889 for anxiety. Thus, whole-intervention nonoverlap indices did not consistently favor RFCBT, whereas the overall pattern of end-point and maintenance effects indicated greater depth and persistence of change following RFCBT. Both interventions were effective in reducing depression, anxiety, and disordered eating; however, RFCBT demonstrated a more favorable pattern in the final magnitude and maintenance of therapeutic change. Targeting rumination as a transdiagnostic cognitive process may therefore enhance the longer-term effectiveness of cognitive behavioral interventions for individuals with obesity, although replication in larger and more controlled studies is warranted.