The relationship between depression and severe obesity is unclear. We examined depression before and after surgically induced weight loss.
Beck Depression Inventory (BDI) questionnaires were completed before and at yearly intervals after gastric-restrictive weight-loss surgery. We used the BDI scores of 487 consecutive patients to identify predictors of depression. Scores from all completed questionnaires were used to follow changes with time. Paired preoperative and 1-year postoperative scores (n = 262) were used to identify predictors of change in BDI score.
For the 487 subjects, the mean ± SD preoperative BDI score was 17.7 ± 9.5. Higher scores, indicating increased symptoms of depression, were found in younger subjects, women, and those with poorer body image. These factors had independent effects. We found no association between BDI and waist circumference or insulin concentrations. High BDI scores correlated with poorer physical and mental quality-of-life measures. Weight loss was associated with a significant and sustained fall in BDI scores, with a mean ± SD score of 7.8 ± 6.5 at 1 year and 9.6 ± 7.7 at 4 years after surgery. Greater falls in BDI score at 1 year were seen in women, younger subjects, and those with greater excess weight loss (combined r2 = 0.10; P<.001). Fall in BDI score correlated with improvement in appearance evaluation (r = −0.31; P<.001).
Severely obese subjects, especially younger women with poor body image, are at high risk for depression. We found sustained improvement with weight loss. These findings also support the hypothesis that severe obesity causes or aggravates depression.