Fasting is dangerous; Especially when you are genetically predisposed to an eating disorder

Why is this important?

You definetly don’t have to look hard to hear about the hype of intermittent fasting. It’s all over social media and chances are people in your social circle are humble bragging about it. As an eating disorder survivor and therapist, I not only find this annoying, I also find it extremely harmful. People start spouting off things they have heard online as if they are science backed facts. Most of the time when you look deeper, the “science” isn’t actually sound- meaning it’s not peer reviewed literature with double blind, longitudinal studies with a large sample size and controlled variables. Often, the “science” pop culture spews about intermittent fasting is related off their own personal experience or a small group of people, with no controlled variables and no long term follow up. This is a big problem. Making claims like this leads to vulnerable people making rash decisions and possibly leading them down a path of harm. When it comes to Eating Disorders, there is even more risk. Those who are predisposed to have an eating disorder (via genetics) can develop a full blown eating disorder when they start any kind of restrictive diet- and yes- intermittent fasting is absolutely a diet. Anything that involves restriction of food is a diet. And even if you don’t have the genetics for an Eating Disorder, there can be serious health consequences.

Here are some of the things that can happen to you that diet and wellness culture won’t tell you when it comes to intermittent fasting.

1. Nutrient deficiencies

Even ‘structured’ intermittent‑fasting regimens (like alternate‑day fasting or time‑restricted eating) can lead to reduced intake of critical micronutrients (calcium, folate, B vitamins, vitamin  C, potassium) unless careful attention is paid to dietary quality. Nutrient deficiencies can weaken your immune system functioning, cause fatigue, anemia, neural tube defects in pregnant people, infertility, cardiovascular disease risk, and increased risk of certain cancers. Doesn’t sound like optimum health or life longevity to me!

2. Higher risk of disordered eating and binge–restrict cycles

A large Canadian study of 2,762 adolescents and young adults found that those who engaged in intermittent fasting over the past 12 months or month had significantly higher rates of eating disorder behaviors and mental health distress across genders, especially women (Ganson et al., 2023).

Another prospective study over five years among adolescent girls reported that fasting episodes (≥24 hours) were stronger predictors of future onset of binge eating and bulimic symptoms than typical dieting behavior (Stice et al., 2008).

3. Disrupted mood, cognition, and stress response

Skipping meals or fasting can trigger elevated cortisol, anxiety, irritability, and blood‑sugar swings. Register dietitians interpret this as evidence of dysregulated stress response and mood disturbance (Harrison & Ball, 2020). This certainly won’t help you navigate stressful life seasons, may exacerbate existing mental health conditions or, as mentioned earlier, trigger an eating disorder.

4. real or self inflicted famine?

Something else to think about here is that your body cannot tell if you are in a real or self inflicted famine. Your body will respond by lowing your metabolism and shutting down other “non-essential” body functions. Your mind will start to obsess about when and what you will eat (some call this food noise, but it’s really a sign of mental hunger). You might even feel “addicted” to food, but food addiction has been debunked many times and is not real even though it might feel real. Another blog post coming soon on that! You can read more about the psychology of hunger here: https://www.apa.org/monitor/2013/10/hunger

Final Thoughts

• Research shows fasting can lead to micronutrient gaps, causing serious health risks (Wallerer & Schwingshackl, 2025).

• It's associated with increased risk of disordered eating (Ganson et al., 2023; Stice et al., 2008).

• It can worsen mental health and stress regulation, including cortisol spikes and blood sugar dysregulation (Harrison & Ball, 2020).

• And there's still uncertainty about long-term cardiovascular safety, given mixed or limited data (Dasgupta & Soto, 2024)

• Folks with eating disorders or a genetic predisposition to one should seriously consider the divesting impacts intermittent fasting could have on them.

• Just because an eating style is trending, does not mean it is healthy! Protect your recovery at all costs.

References

• Ganson, K. T., et al. (2023). Intermittent fasting: describing engagement and associations with eating disorder behaviors and psychopathology among Canadian adolescents and young adults. Psychiatric News, 58(02). Retrieved January 26, 2023. PubMed+2Psychiatry Online+2PMC+2PMC+2Reddit+2PubMed+2

• Harrison, C., & Ball, J. (2020, January 10). 8 scary things that could happen to your body when you skip meals. EatingWell. eatingwell.com

• Stice, E., Presnell, K., & Spangler, D. (2008). Fasting increases risk for onset of binge eating and bulimic pathology: a 5‑year prospective study. International Journal of Eating Disorders, 41(7), 50–57. https://doi.org/10.1002/eat.20593PMC+2PubMed+2Reddit+2

• Wallerer, S., & Schwingshackl, L. (2025). Impact of intermittent fasting on micronutrient intake and adequacy: evidence from ADF and TRE trials. Current Opinion in Clinical Nutrition & Metabolic Care, (advance online publication). https://doi.org/10.1097/MCO.0000000000001148 Lippincott Journals