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Is fasting bad for you? The side effects of fasting are implied by an empty plate of food.
December 16, 2021

Is Fasting Bad For You? Why Intermittent Fasting is a Dangerous Fad

What Is Intermittent Fasting?

Intermittent fasting is a pattern of eating that includes regular periods of fasting. Unlike traditional diets, intermittent fasting does not include any rules on what foods “should” or “should not” be eaten; instead, it specifies when and when not to eat. Participants limit their eating to a certain window of time—for example, only eight hours per day or even alternate days of the week—and do not eat for the remainder of the time. 

In the last several years, the trend of intermittent fasting has become increasingly popular. Proponents of intermittent fasting tout its promises of improved health and weight loss. However, the notable dangers of intermittent fasting are often left out in conversations about the subject. The risks of intermittent fasting may not be readily apparent in our society that celebrates weight loss at any cost, so in this article, we will cover the potential negative side effects of intermittent fasting, including the dangers for those at risk of or suffering from an eating disorder.

Is Intermittent Fasting Good for You? 

The evidence of the long-term effectiveness and safety of intermittent fasting is still unknown. Many studies that have shown any improvement in certain health issues were done on mice, which limits what we know about the impact or positive side effects of intermittent fasting on humans. The majority of studies involving humans include only small sample sizes tracked over a short span of time. Many report measurable physiological outcomes like short-term weight loss, but they generally ignore any mental and emotional health effects, which is especially detrimental considering how closely linked weight loss and eating disorders can be.

Is Intermittent Fasting Safe?

There are numerous health risks associated with intermittent fasting. Research reveals a range of negative physical and mental side effects of intermittent fasting. Like most restrictive diets, side effects include—but are not limited to—hunger, headaches, fatigue, and mood disturbances. The long-term safety and effectiveness of intermittent fasting are still largely unconfirmed, again, given that most existing studies have involved animals rather than human participants. Current human research is very limited in size and duration, in part because this diet fad is not sustainable. In fact, many people are unable to complete intermittent fasting trials, as demonstrated by the high drop-out rate of intermittent fasting weight loss studies. Most concerning is participants’ heightened risk of developing or exacerbating an eating disorder, a serious issue that should not be overlooked. While intermittent fasting is not itself an eating disorder, it can be considered a form of disordered eating. Placing restrictions around your eating and ignoring hunger cues can easily become a slippery slope into a disordered relationship with food or an eating disorder. 

Is Fasting Bad for You? Understanding the Side Effects of Intermittent Fasting

For some, the negative side effects of intermittent fasting extend beyond temporary discomfort. Not all intermittent fasters will experience these symptoms, though, for some (like those with pre-existing health conditions), the harms might be more pronounced.

The following are some of the negative side effects of intermittent fasting:

Intermittent Fasting Side Effects

Intermittent fasting can lead to physiological changes as the body shifts from glucose to stored fat for energy. During this transition, individuals may experience disruptions in blood sugar levels, such as hypoglycemia (low blood sugar). This risk is heightened in individuals with diabetes. Symptoms of hypoglycemia are unpleasant and wide-ranging. It’s worth noting that untreated hypoglycemia can lead to serious neurological consequences, such as seizures and brain damage.

A favorite idea of diet culture is that weight loss is always a net positive because being thin supposedly equals being healthy. We know this is not the case. But with intermittent fasting’s claims of weight loss and improved metabolism, it’s not hard to see why diet culture has latched on. It’s important to understand that dieting is one of the strongest predictors of disordered eating and the development of an eating disorder. When you rely on external factors to make decisions about food and eating, your connection to your body’s hunger and fullness cues is severed. Besides being associated with the onset of eating disorders, dieting fosters an unhealthy fixation on food and body size and spurs feelings of shame around eating.

Research on Intermittent Fasting’s Claims

You might think, “Not everyone experiences those symptoms,” or “Those symptoms are worth it if that means I’ll lose weight.” Despite the promises of weight loss, however, a recent study published in JAMA Internal Medicine showed no differences in weight loss between those who fasted and the control group of consistent eaters. Most studies on intermittent fasting lack the longer-term research and larger sample sizes needed to support intermittent fasting as an “effective” and sustainable weight loss strategy. 

Intermittent Fasting and Eating Disorders

Though eating disorders have no single cause, a key risk factor is dieting. Limiting your eating to a small window can be seen as an extreme compensatory behavior that can trigger other disordered behaviors or thought patterns, such as body dissatisfaction, the adoption of additional food rules, compulsive exercise, and low self-esteem. What’s more, intermittent fasters can easily become hard on themselves for breaking their fast “too early” or eating “too late.” Any sort of anxiety or shame surrounding diet can be a warning sign of disordered behavior, which can lead to the development of an eating disorder in those susceptible. Depriving yourself of food for an extended period of time can also lead to feeling out of control around food once you’re back in your eating window. An all-or-nothing mindset might ensue, which could feel or look like a binge.

The trend of intermittent fasting is especially harmful for those experiencing or recovering from an eating disorder. Intermittent fasting is a restrictive behavior and is worrying in the ways it overlaps with eating disorders like anorexia, bulimia, binge eating disorder, and OSFED. Fasting is in direct conflict with recovery from an eating disorder. It can also make the likelihood of an eating disorder relapse much more plausible. Recovery is about reconnecting with your body and learning to tune into natural hunger cues, which is exactly what intermittent fasting asks people to ignore. 

Key Takeaways About Intermittent Fasting

  • Challenging Diet Culture: The narrative that equates thinness with health is pervasive and misleading. Intermittent fasting, despite its popularity, propagates this idea by promising improvements in health via weight loss, thereby reinforcing harmful diet culture stereotypes.
  • Adverse Effects of Intermittent Fasting: Intermittent fasting can have many negative physical and mental consequences. These can range from feelings of extreme hunger to headaches, lightheadedness, digestive problems, mood changes, fatigue, low energy, and sleep disturbances. More severe issues may also include malnutrition, dehydration, and hypoglycemia.
  • Unclear Long-Term Safety and Efficacy: The long-term safety and effectiveness of intermittent fasting are unsubstantiated. While some animal studies have shown improvements in certain health issues, these results don’t necessarily translate to humans. Most human studies to date have involved small sample sizes and short durations, often overlooking the mental and emotional health effects, muddying the picture of the combined health impact of intermittent fasting.
  • Increased Risk of Eating Disorders: Intermittent fasting is a restrictive fad diet linked to eating disorder behaviors. While not all participants may experience eating disorder symptoms, the risk increases the longer the diet is followed. Fasting can be considered a restrictive behavior that encourages anxiety, shame, a binge-restrict cycle, and the development of a full-blown eating disorder in susceptible individuals. For those recovering from an eating disorder, intermittent fasting may trigger a relapse and further complicate recovery efforts.

If you or a loved one is struggling with dieting or disordered eating and needs help, Veritas Collaborative is here for you. Give us a call at 1-866-875-5812 or complete our online contact form.