Diet culture is omnipresent in our lives, but it’s always shape-shifting (for instance, people talking about “wellness” rather than weight loss). One of the more recent ways that diet culture has shown up is in the trend of intermittent fasting, or not eating for prescribed hours of the day. Over the past few years, countless people have jumped on the intermittent fasting bandwagon, and for some, it’s been harmless or even helpful—but for others, it’s a slippery slope to disordered eating. So is intermittent fasting an eating disorder? And if not, can those in recovery try it? Let’s unpack.

What is intermittent fasting?

Intermittent fasting is an eating approach that now surpasses the ketogenic (keto) diet in popularity among Americans. Instead of demonizing any one food group (like carbs with keto), intermittent fasting involves rigid rules about when—rather than what—you can eat.

“There’s a length of time in the day when a person chooses to eat, and a length of time they choose to  fast,” explains dietitian Lauren Chaffin, RD. “There are several ‘methods’ with varying time ranges, such as a 16-hour fast with eight hours of eating, or fasting days, in which a person may cut way back on their caloric intake for five days, and then eat in a surplus for the remaining two days of the week.” According to Equip dietitian Rui Tanimura, RD, other intermittent fasters may have one large meal per day and avoid all meals and snacks otherwise.

What are the supposed benefits of intermittent fasting?

Proponents claim that intermittent fasting has several significant health benefits, such as increasing lifespan, improving conditions associated with inflammation (like Alzheimer’s), preventing cancer, and improving heart health. Weight loss, it should probably go without saying, is also high on the list of touted benefits. “Supporters claim that it’s an effective approach to control or change weight, improve metabolism, and to prevent overeating,” Tanimura explains.

While there are studies supporting the benefits of intermittent fasting, it’s not the type of research that shows direct causation (e.g., it may show that intermittent fasting is associated with lower blood pressure, but cannot claim that intermittent fasting itself causes this change) or provides us with data from which we can make evidence-based recommendations.

“Intermittent fasting, just like any other fad diet, has far-reaching claims attached to it,” says Chaffin. “The problem is, the research on intermittent fasting has been done almost exclusively in a lab on animals.” For example, one study showing a link between intermittent fasting and longevity was conducted with fruit flies and another on mice. Research that associated intermittent fasting with improving inflammation-linked diseases like Alzheimer’s and that suggested it could help prevent cancer also used animals.

Chaffin says the reason for the limited number of human trials is because of the restrictive nature of intermittent fasting. “ It’s not sustainable, so many people drop out or are unable to complete the trial,” she explains.

There are some human studies showing positive associations between intermittent fasting and cardiovascular risk factors like diabetes and hypertension, yet they are too small and too short in duration to draw conclusive recommendations. “There’s just simply no way to know the benefits versus risk factors without looking at a large population of people over a long period of time,” Chaffin says. “The studies that do show ‘improvements’ only last somewhere between one to 12 weeks total. Compared to a lifetime, it’s a tiny blip of time.”

When it comes to what the research says about weight loss, it’s more of the same story, with studies being too small and too short to prove the diet “works” in the long run. “Most intermittent fasting research continues to need more longer-term outcomes,” says Tanimura. Moreover, a recent randomized clinical trial examining the effects of intermittent fasting on weight loss for 12 weeks showed no differences in weight loss between intermittent fasters and consistent eaters.

Like all other restrictive diets, intermittent fasting comes with several potential side effects, like extreme hunger, fatigue, insomnia, nausea, and headaches. Plus, research shows that dieting can lead to eating disorders.

Is intermittent fasting an eating disorder?

In short, no, intermittent fasting is not an eating disorder. However, all restrictive diets—including intermittent fasting—can be considered a form of disordered eating. This is because these kinds of rigid food rules foster unhealthy behaviors around food and a hyperfixation on body size, and sever the natural connection between our minds and bodies. “When we use external factors such as the time to tell us when we can and cannot eat, we are telling our bodies that they are not to be trusted, and that the cues and signals they give us can be ignored,” Chaffin explains.

And while intermittent fasting itself is not an eating disorder, it does encourage several eating disorder behaviors. One year-long study of young adults and teens of all genders showed a significant association between intermittent fasting and eating disorder behaviors like compulsive exercise, vomiting, and severe food restriction. Gretchen Wallace, RD, adds that “intermittent fasting involves restriction for a large part of the day followed by a food free-for-all, which could look or feel like a binge.”

While such behaviors and rigidity are often symptoms of eating disorders, not all intermittent fasters will experience eating disorder symptoms. However, “that can change if the diet is followed for a long period of time,” Wallace says. “You won't find intermittent fasting listed as a diagnostic criteria in the DSM, but it can quickly shift from being an experiment for your health into a disordered relationship with food or an eating disorder.”

Can intermittent fasting lead to an eating disorder?

In short, absolutely. What may start out as a genuine attempt to experience health benefits can become a slippery slope that descends into disordered eating patterns. Like any other extreme approach to nutrition, intermittent fasting can increase the risk of developing an eating disorder.

Tanimura tried intermittent fasting herself, and says it was one of the behaviors that ultimately led to her eating disorder diagnosis.  “It is an extreme compensatory behavior that can likely trigger other eating disorder behaviors or attitudes such as body dissatisfaction, a desire to adopt severe restriction methods, binge eating, low self-esteem, food rules, and attempting to ignore and suppress hunger cues,” she says.

Can someone in eating disorder recovery try intermittent fasting?

Imagine someone in recovery from alcohol use disorder attempting to drink only one glass of wine per day: it would likely be a fast track to relapse. As an eating disorder dietitian, this analogy is how I help my clients in recovery understand that going on the next diet du jour may set them up for a relapse.

Plus, the principles of intermittent fasting and eating disorder recovery are in direct conflict with each other. “The components of intermittent fasting do not align with the pillars of eating disorder recovery, such as creating consistent meal and snack times every two to four hours, feeling and honoring our hunger and fullness cues, and removing debilitating food rules,” Tanimura explains.

What’s more, intermittent fasting and other diets are externally driven, taking us further away from our bodies, ourselves, and our values—just like eating disorders do.

“I would never recommend dieting to a person in recovery, and intermittent fasting is going to be particularly triggering due to its similarity to disorders like anorexia, binge eating disorder, bulimia, and OSFED,” Wallace says. “If you’re in recovery from an eating disorder and are interested in the alleged health benefits of intermittent fasting, I suggest talking to an eating disorder clinician about how to incorporate health-promoting behaviors into your recovery rather than pursuing a diet such as intermittent fasting.”

If you or someone you love is struggling with disordered eating or rigid food rules that are interfering with your health and ability to live a full life, it’s important to get help. Speak to your medical provider or schedule a consultation with an Equip team member.

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