Taylor Wark

Taylor Ashley, RP #11063 is a Registered Psychotherapist at MyLife Counselling in Guelph. She works with couples and individuals 11yrs and up through anxiety, depression, and relationship issues. Learn more about Taylor here.

Intermittent Fasting and Eating Disorders: The Dangers of FAD Diets

This past summer, three different clients informed me that their General Practitioners (GP) had suggested intermittent fasting (IF) to them to lose weight: the kicker? All three of these clients were seeing me to work on body acceptance and disordered eating behaviours.

When I heard this my heart sank.

Not just for my clients, but also for GPs who believe this weight loss method is safe to suggest to patients with a history of disordered eating. Misinformation about health and weight being synonymous has fuelled our culture of self-dissatisfaction. When I begin collaborating with clients, I suggest they seek guidance from an eating disorder-informed registered dietician (RD) and encourage the client to establish clear boundaries with their GP around diet and weight discussions.

So, what is the ‘big deal’ with suggesting intermittent fasting to someone with disordered eating behaviours and/or disordered eating mentality?

Let us explore!

Intermittent Fasting (IF) has increased in popularity among influencers, diet gurus, and society to ‘lose weight fast.’ With this trend growing, researchers and clinicians have also seen an increase in eating disorder behaviours and psychopathology (Ganson, Cuccolo, Hallward & Nagata, 2022). Most studies in support of IF exclusively study animal metabolisms, not human metabolisms, and I assure you they do not function the same. The human body goes through a natural fast while we sleep (approximately 8 hours) and processes nutrients from the day in that time.

Intermittent fasting prays on an individual’s perception of control, which is often a key fear in eating disorder psychopathology. Studies have shown that IF is positively associated with ED psychopathology and behaviours among all participants including men, women, and non-binary participants (Cuccolo, et al., 2022).

Eating disorders do not discriminate and neither do the impacts of IF.

When discussing the topic of ‘non-diet-diets,’ most clients present arguments that intermittent fasting has scientific backing, stating it can help with diabetes, other heart diseases, and epilepsy.

I am aware of this research.

This is why my clients and I explore their health histories – do they have any of these diseases or diabetes? If yes, the recommended diet could be a medical concern and not in my scope of practice. But 90% of my clients do not have a medical concern that would warrant these extreme diets, and like taking insulin if you do not medically require insulin, IF as an approach to ‘health’ becomes a concern. When researching FAD diets and perceived health benefits, it’s extremely important to note your individual medical history compared to research studies and what diets are originally intended for.

For example, to help patients with diabetes manage their insulin levels because their bodies cannot produce insulin, the Keto diet was a way to control weight. Once diet culture started to endorse the Keto Diet, marketing promoted it as a ‘fast way to lose weight’ and manage insulin levels in people who were not insulin deficient – all under the guise of health, but also thin equates health.

When specifically challenging IFs benefits, we must look at ED psychopathology. The main underlying thought anomalies with disordered eating include extreme fear of weight gain, body image disturbance, loss of control, and compensatory behaviours (American Psychiatric Association, 2013).

Individuals typically utilize restriction and/or other compensatory behaviours as a means of control over their body, but when these falter (and they always do), the feelings of extreme guilt and shame create an internal hostile environment; our society tends to discuss ‘diet failures.’

IF is about ‘self-control’ and convincing your body it does not need sustenance when it asks for it (via hunger cues). The more we ignore our body’s natural cue the less our body trusts us to keep it alive. Our bodies gravitate into starvation mode regularly (via dieting), it begins to acquire our basic needs by whatever means necessary, which is why diets DO NOT WORK. It is also why individuals tend to crave sweets or fatty foods at 8 pm after ‘eating clean’ all day. Our body requires ALL types of food to properly function and if your body does not get all the food groups during the day, it will experience cravings at night.

Relating this point back to IF, if a person with a history of disordered eating is given a method to ‘lose weight fast’ and instruction to lose weight is simply ‘have self-control,’ well this is an eating disorder client’s dream – I know it was for me. This is how disordered eating often starts, with the client’s internalizing the narrative that weight is determined by calories in and calories out. If they do not lose weight, they assume it’s due to a lack of self-control and internalize the perceived failure. Most eating disorders rely on an individual’s hypervigilance around food restriction and managing calorie intake. When a client is already malnourished, not eating consistently, and in starvation mode, then further restricting caloric intake (eating only once per day), the body does not have the fuel needed to survive, which in turn fuels MORE negative body and food thoughts.

Eating once per day will not get you the calories your body needs to function at full capacity, no matter how balanced the meal is.

Then comes the concern of disrupting natural hunger cues. When the body’s hunger cues are ignored, we stop being able to decipher our natural needs. When clients enter recovery, they struggle with the concept of mechanical eating because they can no longer trust their body to communicate what it needs reliably. Their bodies have learned not to communicate with the mind because the mind will not listen. For survival, the body has stopped functioning. Our body was intended, for survival and storage of food and nutrients. (See Mechanical Vs. Intuitive Eating blog for additional information).

Once this happens, individuals DO NOT lose weight. This ‘plateau’ of weight loss is usually when people become frustrated and begin excessively working out, restricting even more, or participating in other compensatory behaviours that lead to long-term health issues.

Therefore, even when individuals believe they are in control of all calories entering and leaving their bodies, it is still only perceived control. Our body’s job is to keep us alive, and it will always try and get us back to our set point.

So, why is suggesting Intermittent Fasting to clients dangerous?

You are giving individuals a tool to perpetuate the disordered eating cycle, thoughts, and behaviours, under the guise of ‘self-control,’ control for the individual cannot be obtained. This sets up clients for feelings of failure, perceiving themselves as ‘weak,’ and increases the likelihood of nutritional deficiencies.

The goal of healthcare should not be changing our bodies for aesthetic reasons, and if clients come in requesting medications or extreme diets for weight loss, the hope would be for medical professionals to connect patients with eating disorder-informed dieticians, mental health, and medical practitioners. The destructive societal idea that living in a smaller body is healthier needs to end at the source of the misinformation. Only then can we facilitate a healthier lifestyle for everyBODY.


American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (DSM-5®). American Psychiatric Pub.

Ganson, K. T., Cuccolo, K., Hallward, L., & Nagata, J. M. (2022). Intermittent fasting: Describing engagement and associations with eating disorder behaviors and psychopathology among Canadian adolescents and young adults. Eating Behaviors, 47, 101681. https://doi.org/10.1016/j.eatbeh.2022.101681

Taylor Wark

Taylor Ashley, RP  #11063 is a Registered Psychotherapist at MyLife Counselling in Guelph. She works with couples and individuals 11yrs and up through anxiety, depression, and relationship issues. Learn more about Taylor here.

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