The psychological effects of dieting and weight loss have been an area of controversy in obesity. As part of a large multicenter study involving 1944 obese subjects seeking treatment at Italian medical centers, we investigated the effects of weight loss on psychological distress and binge eating in 500 subjects remaining in continuous treatment at different centers with slightly different strategies (78.8% females; age: M=46.2 years, SD=10.8; BMI: M=37.3 kg/m(2), SD=5.6). At baseline and after 12 months all subjects were evaluated by the Symptom CheckList-90 Global Severity Index (SCL-GSI) and by the Binge Eating Scale (BES). In both males and females, weight loss was associated with improved psychometric testing. Changes in SCL-GSI were associated with changes in BMI (beta=0.13; t=2.85; p<0.005), after adjustment for age, gender, initial BMI and center variability. Similarly, BES changes were associated with BMI change (beta=0.15; t=3.21; p<0.001). We conclude that in subjects compliant to follow-up a successful management of obesity, not directly addressing psychological distress, is associated with a significant improvement of both psychological distress and binge eating, linearly related to the amount of weight loss, independently of treatment procedures.