Objective: Depression and obesity are bi-directionally related, eating styles and diet quality are two important factors associated with both. It remains uncertain if and how these two factors can be modified. Therefore the current study aims to investigate whether food-related behavioral activation therapy (F-BA), targeting mood, dietary habits and food related behavior, can improve eating styles, and diet quality and reduce body weight in adults with overweight or obesity and subsyndromal depressive symptoms. Methods: Data were derived from the MooDFOOD prevention trial, a 2x2 factorial RCT investigating the effect of nutritional strategies on prevention of depression. Changes in emotional, uncontrolled, and cognitive restrained eating (Three Factor Eating Questionnaire Revised), Mediterranean Diet Score (MDS), and body weight were analyzed among 1025 adults who either received F-BA or no intervention for 12 months. Intervention effect was tested by longitudinal analysis of covariance using mixed model analysis. Results: The F-BA group showed a small decrease in emotional (β=-5.68, p<.001) and uncontrolled eating (β=-4.05, p=.03), and increase in cognitive restrained eating (β=5.53, p<.01), compared to no F-BA. The effect of the F-BA therapy on emotional and uncontrolled eating was stronger in those with higher baseline depressive symptoms (IDS-SR). The F-BA did also lead to small improvements in MDS (β=1.95, p<.001), but not to change in body weight. Conclusion: Our trial showed no reduction in bodyweight, but provides support for the possibility to improve both unhealthy eating styles and diet quality using an intervention targeting these specifically, although effects were small [Trial registration: clinicaltrials.gov NCT02529423].