Regardless of current weight, a history of obesity, was associated with worse current mental health, which could increase the risk of an early death, said researchers of an early observational study, who suggested that past obesity could be psychologically "scarring".
Dr I Gusti Ngurah Edi Putra, from the University of Liverpool, pointed out that previous studies had indicated that some people who lost weight, and who were no longer classed as having obesity, still "feared being stigmatised" due to having previously had obesity.
"This led us to hypothesise that past obesity may have long-term psychological impacts that persist even after individuals are no longer classified as having obesity," he said in a press briefing.
The research, which has not yet been peer reviewed, was presented orally at the European Congress on Obesity (ECO) in Dublin, Ireland (17-20 May).
Past Obesity Associated with Psychological 'Scarring'
To test the novel 'weight scarring' hypothesis, the researchers used data of over 40,000 individuals, including 29,047 individuals from the National Health and Nutrition Examination Survey (NHANES) and 11,998 individuals from the Health and Retirement Study (HRS). The data included information on past and current weight, height, symptoms of depression and other psychological wellbeing indicators (in the HRS), and mortality.
"Past obesity was associated with greater depressive symptoms," the researchers found. In both NHANES and HRS, individuals with a history of obesity scored more highly when asked about symptoms of depression than those without a history of obesity, said the researchers. Then they looked at whether the psychological consequences of past obesity might explain why the condition was associated with premature death.
"In the HRS, past obesity was associated with a range of psychological well-being indicators, including an index of impaired psychological wellbeing which combined some indicators – e.g., depressive symptoms, loneliness, anxiety, hopelessness – independent of current weight status," Dr Putra pointed out.
The association between past obesity and psychological wellbeing across studies remained in participants who were no longer classified as having obesity, indicating that "past obesity may be psychologically scarring", the researchers said.
"A history of obesity increased the risk of early death by around 30% (31% in NHANES and 34% in HRS), independent of current weight status," Dr Putra told the briefing.
He explained that this association was partly due to the poorer psychological health (e.g., high depressive symptoms, impaired psychological wellbeing) of the individuals with a history of obesity.
"The psychological burden of past obesity might explain why past obesity was associated with increased mortality," proposed Dr Putra.
Psychological Support Should Continue After Weight Loss
The researchers said their results were consistent with their hypothesis that the shorter lifespan associated with past obesity is partly due to the psychological consequences of the condition.
"Our findings suggest that obesity may be psychologically 'scarring' and that these psychological 'scars' may increase the risk of an early death, explained Dr Putra.
"Ensuring people with obesity receive psychological support, even after experiencing weight loss, may reduce the risk of subsequent ill health," suggested the researchers.
Dr Putra emphasised that the findings, based on observational data, were preliminary, and that only associations, not causation, could be established. He added that further research confirming the findings was needed.
No funding was declared for the study, as the authors declared no conflicts of interest.