Obesity develops from a combination of environmental effects and genotype, both of which can present as heightened risk factors in people with mental illness.
Obesity also brings with it higher risks of type 2 diabetes and cardiovascular disease, which can further affect psychological well-being.
Subsequently, according to the Arizona Department of Health Services, people with mental illness die 25 years earlier than those without mental illness due to obesity-related conditions.
While rates of obesity are increasing globally, with 39% of adults overweight or obese, there appears to be a link between mental illness and obesity. According the World Health Organization, patients with a history of attention-deficit/hyperactivity disorder (ADHD) have a greater chance of becoming obese.3
Furthermore, a Swedish study found that obese patients suffered from depression as intense as those experiencing chronic pain. Therefore, a history of mental illness may increase the risk of obesity, while obesity may increase an individual's chances of developing a psychiatric disorder.
The reasons cited for the link between obesity and psychiatric problems are unsurprising: poor self-image, physical inactivity, the biological disruptions caused by obesity, and the social stigma related to being overweight all contribute to a predisposition to mental illness.
Depression and low self-esteem have been observed in obese patients around the world, even when there has been no previous history of mental illness. Studies conducted at the Texas Health Science Center and by the UK's National Obesity Observatory (NOO) are among the many research programs confirming that the obese are at greater risk for depression.
The researcher postulated that this is a result of women being inclined to be more distressed about the perception of being overweight than men, which makes them more susceptible to mental illness.
Race is another factor feeding into the relationship between obesity and mental illness. A study conducted by researchers at University College London found that girls from African groups were not as affected by being overweight as white girls since being overweight did not lead to social stigma in their society.
Metabolic syndrome, which arises from insulin resistance due to increased abdominal fat levels, is especially prevalent in patients with schizophrenia. The link between psychiatric medication and obesity may be due to the fact that psychotropic drugs not only contribute to weight gain but also create changes in the sensitivity of the body to insulin.
Shrivastava and Johnston observed this phenomenon and noted that weight gain caused by psychiatric medications further exacerbated the psychological problems experienced by patients.10 It would be easy to assume that the choice of medication is responsible for this, but almost all psychiatric medications cause weight gain, according to a meta-analysis by Bak and colleagues.
According to Taylor and colleagues, linking all cases of obesity caused by mental illness to medication is too simplistic a view. Psychiatric disorders such as depression, attention deficit disorder, and posttraumatic stress disorder can lead to weight gain owing to “comfort eating,” a lack of interest in preparing healthy meals, and impulsive eating habits. The effect caused by the stress hormone, cortisol, emitted during times of distress also plays a role in weight gain.
A complex spectrum of factors contributes to the link between obesity and mental illness. Obesity has debilitating effects on both physical and mental health, and can lead to full-blown mental illness as a result of poor self-image and physical illnesses.
In turn, psychiatric complaints can also cause obesity as a result of medication effects, hormone imbalances, and the behavioral issues that result from psychiatric disorders.
Information from the following references:
Lutterman T, Ganju V, Schacht L, et al. Sixteen state study on mental health performance measures. DHHS Publication No. (SMA) 03-3835. Rockville, MD: Center for Mental Health Services, Substance Abuse and Mental Health Services Administration, 2003.
Dickerson F, Brown C, Kreyenbuhl J, et al. Obesity among individuals with serious mental illness. Acta Psychiatrica Scand. 2006;113(4):6-313.
World Health Organization. Obesity and overweight fact sheet. 2005. Available at: http://www.who.int/mediacentre/factsheets/fs311/en/. Accessed February 26, 2016
Karlsson J., Sjöström L, Sullivan M. Swedish obese subjects (SOS) – an intervention study of obesity. Two-year follow-up of health-related quality of life (HRQL) and eating behavior after gastric surgery for severe obesity. Int J Obes Relat Metab Disord. 1998;22(2):113-126.
Pagoto SL, Curtin C, Lemon SC, et al. Association between adult attention deficit/hyperactivity disorder and obesity in the US population. Obesity. 2009;17(3):539-544.
National Obesity Observatory. Obesity and mental health. March 2011. http://www.noo.org.uk/uploads/doc/vid_10266_Obesity%20and%20mental%20health_FINAL_ 070311_MG.pdf. Accessed February 26, 2016.
van der Merwe M. Psychological correlates of obesity in women. Int J Obes Relat Metab Disord. 2007;31:S14-S18.
Wardle J, Cooke L. The impact of obesity on psychological well-being. CR-UK Health Behaviour Unit, Department of Epidemiology and Public Health, University College London; 2005.
Newcomer J. Metabolic syndrome and mental illness. Am J Managed Care. 2007;13(7 Suppl):S170-177.
Shrivastava A, Johnston ME. Weight-gain in psychiatric treatment: risks, implications, and strategies for prevention and management. Mens Sana Monographs. 2010;8(1):53-68.
Bak M, Fransen A, Janssen J, van Os J, Drukker M. Almost all antipsychotics result in weight gain: a meta-analysis. PLoS ONE. 2014;9(4): e94112.
Taylor VH, McIntyre RS, Gary Remington MD, Levitan RD, Sharma AM. Beyond pharmacotherapy: understanding the links between obesity and chronic mental illness. Can J Psychiatry. 2012;57(1):5.