Intermittent Fasting: A fast track to disordered eating?

BY: Elisa Klein, MSW, MPH, LCSWA

DATE: October 26, 2016

Just recently, Jewish people around the world celebrated the holiday of Yom Kippur, or day of repentance. This solemn holiday is a day of fasting, and many Jews will fast for a 24-hour period in observance. Fasting for religious or spiritual purposes is not uncommon. Many religions engage in fasting as a method of purification, tradition, and discipline.

However, fasting, even for just 8 hours, can be uncomfortable at a minimum. When I observe Yom Kippur, I inevitably start to get “hangry,” which is that awful combination of hungry and angry. As my blood sugar drops throughout the day, I get short-tempered, irritable, and tired. I may get a headache, and without any food or drink, I’ll definitely get dry-mouth! It’s hard for me to imagine enduring this feeling more than once a year, yet alone multiple times a week. But a new diet trend, called intermittent fasting, encourages just this.

Intermittent fasting, sometimes called the 5:2 diet or alternate-day fasting, encourages five days of “normal” calorie consumption and 2 days of extreme calorie restriction. This diet became popular when celebrity Jimmy Kimmel credited it for his significant weight loss. Overnight, it seemed like this diet trend was everywhere, with claims that incorporating fasting not only helps with weight loss, but also can improve immune function and low energy levels.

Intermittent fasting contributes to weight loss because during restriction, the body shifts from using glucose for fuel to using fat for fuel. Sounds simple and effective, right? Wrong! For those of us in the eating disorder field, intermittent fasting sounds like a fast track to a big problem.

The first problem is that the research simply is not there. Thus far, there have been limited studies on intermittent fasting and its long-term health effects. We can expect more information from the research field as fasting becomes more popular, but right now we simply don’t understand the risks or benefits.

Secondly, people who fast are without a doubt…hungry! When the fast is ultimately broken, they might over-eat, binge-eat, or consume foods that are not nutritionally sound because they are famished.

Finally, and perhaps most importantly, for those who have an eating disorder or are at risk of developing one, intermittent fasting can create an unhealthy obsession with food. It is easy to see how someone could obsess or ruminate over what and when to eat. Moreover, intermittent fasting does not seem all that different from bulimia, where one compensates for eating by engaging in a behavior to cleanse or purge the body of food and/or calories.

“All-or-nothing” diets and/or behaviors are rarely the answer when it comes to nutrition and health. Intermittent fasting is no different. So before you jump on fasting bandwagon, remember that your body requires food for fuel on a daily basis. And as always, if you are considering weight loss, or if you are struggling with finding nutritional balance, consult a health professional.


Harvie, MN, Pegington, M, Mattson, MP, et al. The effects of intermittent or continuous energy restriction on weight loss and metabolic disease risk markers: a randomized trial in young overweight women. Int J Obes (Lond). 2011 May;35(5):714-27.

Klempel, MC, Kroeger, CM, Varday, KA. Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cardio-protection as ADF with a low-fat diet. Metabolism. 2013 Jan;62(1):137-43