What Makes Intermittent Fasting So Concerning

If you look into any nutrition or dieting advice online, you're sure to come across numerous headlines boasting the benefits of intermittent fasting, also referred to as IF. In case you're unfamiliar with intermittent fasting, it is true to its name and entails only eating during a specific gap of time according to John Hopkins Medicine. The source describes different techniques such as minimizing the hours you eat during the day, or limiting food consumption on certain days each week. Neuroscientist Mark Mattson suggests that when the body has used up its sugar stores, it switches to burning fat for energy.

Kristen Carli, Registered Dietitian Nutritionist and owner of Camelback Nutrition & Wellness, focuses her practice on finding methods to build a sustainable lifelong balance with food and other elements of daily life. She has not jumped on the intermittent fasting train, and believes it is best to take a step back and look at the various aspects involved with this method. Carli describes that "IF, like most fad diets, has some critical flaws that can make this diet trend dangerous for some individuals." Of course, diet and weight loss publications mostly disregard this notion, flaunting the appeal of the method.

What are some of the effects of IF?

It's not hard to find lists of advantages of IF, such as one by Healthline which includes weight loss, decreased inflammation and insulin resistance, as well as increased metabolism and lifespan. The effects are all described as potential benefits and many have only been tested minimally in humans and are often extrapolated from animal studies. Aside from the fact that humans and animals have different reactions to certain states, IF can have a range of consequences depending on the person.

For example, Carli explains that in some people, intermittent fasting can result in "changes in hormone production, including a marked increase in the stress hormone cortisol." While many people opt for IF, finding the lack of food restrictions less stressful than something like the keto diet, it could actually be doing the opposite to your body. Even worse, a study in the publication Obesity Research suggests that higher levels of cortisol are associated with fat storage. On top of a possible rise in stress levels, Carli notes that "intermittent fasting can cause disruption in mood and increased irritability." She explains this occurrence as being "triggered by low glucose levels", which Carli explains are "the brain's preferred fuel source."

Who shouldn't try intermittent fasting?

Kristen Carli shares the results of a study by Frontiers in Nutrition that measured psychological effects in healthy women, which concluded that aside from some increases in irritability, positive results were also indicated. The study found a heightened sense of achievement, reward, and pride described by the participants with regards to the challenge of fasting.

Unfortunately this result is not all positive, since the research suggested it might create a bridge between fasting and disordered eating, such as extreme restriction (via Frontiers in Nutrition). Carli notes that these behaviors could "produce a negative relationship with food." This connection was demonstrated by the Journal of Abnormal Psychology, which found that teenage girls who fasted to control weight, were more likely to engage in future behaviors associated with bulimia and disordered eating. In line with these results, John Hopkins Medicine as well as many other institutions, advise against trying intermittent fasting if you have a history of eating disorders.

Aside from certain risk factors, Christie Williams, registered dietitian nutritionist, tells John Hopkins Medicine that intermittent fasting can be an advantageous shift for many people. Nevertheless, Carli warns, "Dieting can be confusing, especially with all the diet trends emerging, but if a diet sounds too good to be true, it probably is too good to be true." The best diet and lifestyle plan is one that you can continue healthily and sustainably, which for many people is not the case with intermittent fasting.