Today’s post comes from Rebecca Christensen. Rebecca is a PhD Student in the Dalla Lana School of Public Health, Epidemiology program at the University of Toronto. She is also one of the current Chapter Representative on the OC-SNP National Executive.

Weight and mental health are two important health factors that are deeply entwined, and this makes it hard to determine which one is the predisposing factor, or in other words similar to the chicken and the egg problem – it is difficult to determine which comes first. There are a lot of reasons for this, and in this blog post I hope to give you an idea as to why this might be. This blog post is not meant to be exhaustive and will not be in relation to a specific mental health disorders. This is more meant to provide some explanation as to why the relationship between weight and mental health is so complex.

Certain mental health disorders have symptoms that can be associate with weight gain. For example, lethargy, decreased sleep, excessive sleep, and increased appetite are all symptoms of mental health disorders1. However, mental health disorders can also have symptoms that could be associated with losing weight, such as decreased appetite, or increased energy1. What can make this even more complicated is that the same mental health disorder can have symptoms that both increase and decrease weight. Symptoms of depression, for example, can include both increased or decreased appetite, and/or sleep1.  

Treatment for mental health disorders can take a variety of forms, and this can include the use of pharmaceuticals. A recent (2018) review explored the weight effects of commonly prescribed medications in Canada2. The authors of this review remarked that the majority of antidepressants, and antipsychotics are associated with moderate (>1 kg) or significant (>3 kg) weight gain, with few alternatives that promote weight loss2. This can mean that in addition to the symptoms of the mental health disorder promoting weight gain, established treatments may further exacerbate this.

There are clear examples of how having a mental health disorder can either increase or decrease weight, as described above. And while excess weight can also increase an individual’s risk of developing a mental health disorder, the etiology behind this is less clear. Research has observed that individuals who have genes that are associated with having a high BMI are at a greater risk of having depression, whether or not they also had genes that predisposed them to other cardiometabolic disorders such as diabetes3. In addition to biological determinants of weight, weight stigma can also promote mental health disorders. Research has observed a greater risk of anxiety4 and depression5 in individuals who have experienced weight stigma.  

Thankfully, there are treatment options that can be beneficial both to weight and mental health. For example, treatment for depression can incorporate physical activity, which is an important component of any weight management intervention. And while it is true that few weight loss promoting mental health medications exist, one of those that do is also part of a combination medication for weight management (i.e. Contrave, which is a combination of bupropion (a common SSRI antidepressant) and naltrexone (an opioid agonist))6. Thus, while we may not be able to tease apart the relationship to determine which one is the more important predisposing factor, we still have ways to successful manage both of these conditions simultaneous.  

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  1. DSM 5. DSM 5. American Journal of Psychiatry (2013). doi:10.1176/appi.books.9780890425596.744053
  2. Wharton, S., Raiber, L., Serodio, K., Lee, J. & Christensen, R. A. Medications that cause weight gain and alternatives in Canada: a narrative review. Diabetes, Metab. Syndr. Obes. Targets Ther. Volume 11, 427–438 (2018).
  3. Tyrrell, J. et al. Using genetics to understand the causal influence of higher BMI on depression. Int. J. Epidemiol. (2018). doi:10.1093/ije/dyy223
  4. Hatzenbuehler, M. L., Keyes, K. M. & Hasin, D. S. Associations between perceived weight discrimination and the prevalence of psychiatric disorders in the general population. Obesity (2009). doi:10.1038/oby.2009.131
  5. Hackman, J., Maupin, J. & Brewis, A. A. Weight-related stigma is a significant psychosocial stressor in developing countries: Evidence from Guatemala. Soc. Sci. Med. (2016). doi:10.1016/j.socscimed.2016.05.032
  6. Valeant. Contrave Product Monograph. (2018).