The psychological legacy of past obesity and early mortality: evidence from two longitudinal studies

Background: We test a novel ‘weight scarring’ hypothesis which suggests that past obesity leaves a ‘scar’ on current psychological well-being and this psychological scarring leads to meaningful health consequences. Across two nationally representative studies, we tested whether past obesity forecasts current psychological outcomes and whether these psychological consequences explain why obesity is associated with subsequent early mortality.

Methods and Findings: Data were from the National Health and Nutrition Examination Survey (NHANES) (n=29,047) and the Health and Retirement Study (HRS) (n=11,998). Past obesity was defined based on maximum lifetime weight in NHANES and the highest weight from past study waves in the HRS. Current depressive symptoms in both studies and an index of impaired psychological well-being combining 10 psychological measures in the HRS were analysed. We found that past obesity was associated with greater depressive symptoms after controlling for current weight status and in analyses limited to those who were no longer classified as having obesity in NHANES (β = 0.17; 95% CI: 0.13, 0.22) and HRS (β = 0.20; 95% CI: 0.08, 0.31). In the HRS, past obesity predicted a range of current negative psychological outcomes, including an index of impaired psychological well-being (β = 0.16; 95% CI: 0.05, 0.27). Past obesity predicted early mortality in both NHANES and HRS (HR = 1.31; 95% CI: 1.16, 1.48 and HR = 1.34; 95% CI: 1.20, 1.50, respectively). Depressive symptoms and impaired psychological well-being partly mediated the association between past obesity and the risk of premature mortality.

Conclusions: Our findings suggest that past obesity may be psychologically ‘scarring’ and that the psychological legacy of past obesity is associated with raised mortality risk. Ensuring people with obesity receive psychological support even after experiencing weight loss may now be important.