Obesity and Mental Health: A Surprisingly Strong Connection

A new large-scale study finds obesity often precedes mental-health disorders.

About one in three people worldwide are overweight and there is increasing evidence that obesity as a physical health issue may also be connected to many mental health problems. A new study, published in the scientific journal “Translational Psychiatry” (Leutner et al., 2023), was focused on investigating the link between obesity and mental health problems in a huge dataset of several million people.

Obesity and mental health disorders in millions of people

In the study, first-authored by Michael Leutner from the Medical University of Vienna, the researchers obtained an impressively large dataset to get replicable and statistically robust results. Data were obtained from the Austrian national registry of inpatient services and analyzed for the years between 1997 and 2014. Overall, data from 161,185 patients with obesity and from 3,006,526 patients without obesity were analyzed in the study. Many obese patients showed co-occurring physical diagnoses such as diabetes, high blood pressure, a variety of heart problems, and insomnia. In addition to these physiological diagnoses, patients with obesity also showed significantly higher percentages for many psychiatric diagnoses than patients without obesity.Being obese was associated with a significantly increased risk for:

• nicotine use disorder
• schizophrenia
• schizoaffective disorder
• bipolar disorder
• depressive episodes
• recurrent depression
• dysthymia
• anxiety disorders
• somatization disorders
• eating disorders
• personality disorders

This finding is quite striking in that it clearly shows that obesity is not only linked to mental health disorders related to food consumption such as eating disorders, but that it is very broadly connected to many different mental health problems.

Obesity on average occurs before the mental health disorder diagnosis

Subsequently, the scientists analyzed whether on average patients first were diagnosed with obesity or first were diagnosed with a mental health disorder. One could think that some mental health disorders such as depression may lead to less motivation to exercise and also changes in eating behavior, which may increase the risk of becoming obese. On the other hand, being obese may also be a risk factor to develop a mental health disorder. These results were very clear: Obesity was significantly more often the diagnosis that was received first, and the mental health disorder diagnosis was typically the diagnosis received second. While the study design does not allow to make causal conclusions, this directionally of the timing between obesity and mental disorders suggests that at least to some extent obesity may increase the risk for mental-health problems. In addition to these findings, the research team also observed differences between men and women, with women having higher risks for all investigated disorders except schizophrenia and nicotine addiction. This suggests a particularly strong connection between obesity and mental health disorders in women.

An increasing need for mental health support for people suffering from obesity

The scientists suggested that the results of their study have important implications for the treatment of mental health disorders. In particular, they suggested that it is essential to be aware of the potential that obese patients also show mental health disorders. Therefore, obese patients should be screened for mental health problems (e.g., by asking them to fill out clinical questionnaires) in order to facilitate fast and proper psychological treatment. Moreover, prevention programs specifical targeted at obese patients should be implemented to prevent mental health disorders.

ReferencesLeutner M, Dervic E, Bellach L, Klimek P, Thurner S, Kautzky A. (2023). Obesity as pleiotropic risk state for metabolic and mental health throughout life. Transl Psychiatry, 13, 175.