Author: Delaney Rivard, Undergraduate Student in the Department of Neuroscience
Trigger Warning: This post discusses eating disorders, including behaviours such as food restriction, bingeing, purging, and compulsive exercise, as well as references to substance use and mental health challenges. If you are currently struggling with an eating disorder or related concerns, please read with care and consider accessing support from the list below.
If you or someone you know is struggling with an eating disorder, the following organizations and services offer support, information, and pathways to care.
Hopewell Eating Disorder Support Centre of Ottawa
Connex Ontario: Discover Mental Health, Addiction, and Problem Gambling Services
Sheena’s Place: Online Support Groups for Eating Disorders
Body Brave: Virtual Support for Eating Disorders
As National Eating Disorder Awareness Week passes, we are called to challenge harmful myths about eating disorders. One of the most persistent is the belief that they are simply about vanity, control, or a lack of willpower. In reality, eating disorders are serious mental health conditions that can have devastating physical and emotional consequences 1.
Increasingly, research suggests that the way these disorders persist has important similarities to substance use and behavioural addictions. Eating disorders such as anorexia nervosa and bulimia nervosa involve behaviours like severe food restriction, bingeing, purging, and compulsive exercise 2. While body image pressures and cultural ideals often contribute to how they begin, these factors alone do not explain why the behaviours can be so difficult to stop, even when someone wants to recover. Studies show that motivation alone does not always reduce certain symptoms, especially purging behaviours 3. This pattern mirrors what is seen in substance use disorder, where understanding the harm does not automatically make the behaviour easier to quit.
So what keeps these behaviours going?
Part of the answer may lie in how the brain responds to them. Our brains are wired to repeat behaviours that bring relief or reward. When something reduces stress, numbs emotional pain, or creates even a brief good feeling, the brain can begin to reinforce it. Research shows that behaviours common in eating disorders, such as fasting, intense exercise, and binge–purge cycles, activate the brain’s natural reward and stress-relief systems4,5,6. Over time, this can strengthen the urge to repeat those behaviours, much like how substances reinforce patterns in substance use disorder.
In substance use disorder and behavioural addictions, repeated use changes the brain’s reward system, making cravings stronger and stopping harder. Emerging evidence suggests that repeated eating disorder behaviours may also shape the brain in similar ways 7.
This does not mean eating disorders are identical to substance use disorders, but it does mean they may share reinforcement loops that make behaviours feel compelling, automatic, and difficult to stop.
Understanding this parallel changes the conversation. If behaviours are being reinforced by the brain’s own reward systems, recovery cannot be reduced to “just eat” or “just stop”. Eating disorders are complex. They are influenced by culture, identity, trauma, biology, and neurological reinforcement.
Overall, the evidence indicates that while psychological and sociocultural factors contribute to the development of eating disorders, they do not fully explain the persistence of behaviours such as restriction, binge–purge cycles, and compulsive exercise. Converging findings show that these behaviours engage reward systems and drive reinforcement. Similar reinforcement-driven neuroadaptations are well established in behavioural disorders and substance use disorder, supporting the view that repeated engagement in eating disorder behaviours may strengthen reward pathways in ways that sustain symptoms over time.
Although further research is needed, the current evidence supports a model in which reward system changes similar to that observed in substance use disorder contributes to eating disorder pathology.
References:
1. Carlson, J. L., & Lemly, D. C. (2024). Medical Considerations and Consequences of Eating Disorders. Focus: Journal of Life Long Learning in Psychiatry, 22(3), 301–306. https://doi.org/10.1176/appi.focus.20230042
2. American Psychiatric Association (Ed.). (2022). Diagnostic and statistical manual of mental disorders: DSM-5-TR (Fifth edition, text revision). American Psychiatric Association Publishing.
3. Clausen, L., Lübeck, M., & Jones, A. (2013). Motivation to change in the eating disorders: A systematic review. International Journal of Eating Disorders, 46(8), 755–763. https://doi.org/10.1002/eat.22156
4. Marrazzi, M. A., Bacon, J. P., Kinzie, J., & Luby, E. D. (1995). Naltrexone use in the treatment of anorexia nervosa and bulimia nervosa. International Clinical Psychopharmacology, 10(3), 163–172. https://doi.org/10.1097/00004850-199510030-00005
5. Boecker, H., Sprenger, T., Spilker, M. E., Henriksen, G., Koppenhoefer, M., Wagner, K. J., Valet, M., Berthele, A., & Tolle, T. R. (2008). The Runner’s High: Opioidergic Mechanisms in the Human Brain. Cerebral Cortex, 18(11), 2523–2531. https://doi.org/10.1093/cercor/bhn013
6. Wang, Y., & Wu, R. (2022). The Effect of Fasting on Human Metabolism and Psychological Health. Disease Markers, 2022, 5653739. https://doi.org/10.1155/2022/5653739
7. Jiook Cha, Jaime S. Ide, F. Dubois Bowman, Helen B. Simpson, Jonathan Posner, & Joanna E. Steinglass. (2016). Abnormal reward circuitry in anorexia nervosa: A longitudinal, multimodal MRI study. 37. https://doi.org/10.1002/hbm.23279
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