5 Times You Should Avoid Intermittent Fasting

plate three-quarters full

Published January 05, 2022

Intermittent fasting has greatly increased in popularity and praise over the last few years. However, there are certain cases when you shouldn’t attempt intermittent fasting. 

Intermittent fasting is the practice of following a schedule of fasting (not eating for extended periods of time) and regular eating. The 16/8 method and the 5:2 diet are common patterns of intermittent fasting. The 16/8 method involves rotating between 16 hours a day of fasting and 8 hours of eating. The 5:2 diet involves eating normally for 5 days of the week and reducing your calorie intake for 2 days. 

Some health experts recommend intermittent fasting for its ability to support brain health, reduce inflammation,1 and improve blood pressure.2 However, there are certain groups of people who may be harmed by intermittent fasting. Avoid intermittent fasting if any of the following characteristics apply to you:   

  1. You have a history of disordered eating or eating disorders. Intermittent fasting requires intentional restriction of food and ignoring of hunger signals. These practices may be triggering if you’ve had an eating disorder and may lead to new eating disorder behaviors.3,4   

  2. You’re pregnant, breastfeeding, or trying to become pregnant. Pregnant or breastfeeding people have increased energy needs and shouldn’t engage in calorie restriction.5 Intermittent fasting may also reduce your chances of becoming pregnant and should be avoided if you’re trying to conceive.6  

  3. You have diabetes or blood sugar issues. Fasting may cause drastic changes in blood sugar levels and increase your risk of dangerously low blood sugar.7  

  4. You’re under 18 years of age. Children and teenagers need plenty of calories for proper development and growth. Avoid fasting if you’re still growing due to the risk of low calorie intake.8  

  5. You take blood pressure or heart disease medications. Fasting increases the chances that your blood level of electrolytes may get dangerously low. 9 People on blood pressure and heart diseases medications may be especially prone to low electrolytes from fasting.10 Examples of electrolytes include sodium and potassium. 

Intermittent fasting isn’t for everyone. Fortunately, there are many other ways to tend to your health that don’t require fasting. Schedule an appointment at Bastyr Center for Natural Health or Bastyr University Clinic for a personalized nutrition plan that works for your needs. 


Yael Gutin is a Dietetic Intern at Bastyr University. She believes the key to a healthy lifestyle is practicing sustainable habits that nourish you physically, mentally, and emotionally without compromising a joyful relationship with food or your body.   




  1. Stockman MC, Thomas D, Burke J, Apovian CM. Intermittent Fasting: Is the Wait Worth the Weight? Curr Obes Rep. 2018;7(2):172-185. doi:10.1007/s13679-018-0308-9 

  1. Wilkinson MJ, Manoogian ENC, Zadourian A, Lo H, Fakhouri S, Shoghi A, Wang X, Fleischer JG, Navlakha S, Panda S, Taub PR. Ten-Hour Time-Restricted Eating Reduces Weight, Blood Pressure, and Atherogenic Lipids in Patients with Metabolic Syndrome. Cell Metab. 2020 Jan 7;31(1):92-104.e5. doi: 10.1016/j.cmet.2019.11.004. Epub 2019 Dec 5. PMID: 31813824; PMCID: PMC6953486. 

  1. Cuccolo K, Kramer R, Petros T, Thoennes M. Intermittent fasting implementation and association with eating disorder symptomatology. Eat Disord. 2021 Jun 30:1-21. doi: 10.1080/10640266.2021.1922145. 

  1. Stice E, Davis K, Miller NP, Marti CN. Fasting increases risk for onset of binge eating and bulimic pathology: a 5-year prospective study. J Abnorm Psychol. 2008;117(4):941-946. doi:10.1037/a0013644 

  1. Alaa Alkhalefah, Warwick B. Dunn, James W. Allwood, Kate L. Parry, Franchesca D. Houghton, Nick Ashton, Jocelyn D. Glazier; Maternal intermittent fasting during pregnancy induces fetal growth restriction and down-regulated placental system A amino acid transport in the rat. Clin Sci (Lond) 11 June 2021; 135 (11): 1445–1466. doi: https://doi.org/10.1042/CS20210137 

  1. Kumar S, Kaur G. Intermittent fasting dietary restriction regimen negatively influences reproduction in young rats: a study of hypothalamo-hypophysial-gonadal axis. PLoS One. 2013;8(1):e52416. doi: 10.1371/journal.pone.0052416. Epub 2013 Jan 29. PMID: 23382817; PMCID: PMC3558496. 

  1. Corley B, Carroll R, Hall R, Weatherall M, Parry-Strong A, Krebs J. Intermittent fasting in Type 2 diabetes mellitus and the risk of hypoglycaemia: a randomized controlled trial. Diabet. Med. 2018 Feb;35, 588– 594. https://doi.org/10.1111/dme.13595 

  1. Intermittent fasting: What is it, and how does it work? Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/wellness-and-prevention/intermittent-fasting-what-is-it-and-how-does-it-work. Published 2021. Accessed November 3, 2021. 

  1. Fasting: How Does It Affect Your Heart and Blood Pressure? Cleveland Clinic. https://health.clevelandclinic.org/fasting-how-does-it-affect-your-heart-and-blood-pressure/. Published February 3, 2020. Accessed November 3, 2021. 

  1. Not so fast: Pros and cons of the newest diet trend. Harvard Health. https://www.health.harvard.edu/heart-health/not-so-fast-pros-and-cons-of-the-newest-diet-trend. Published July 31, 2019. Accessed November 3, 2021.