Intermittent fasting linked to disordered eating, compulsive exercise

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A recent study suggests that intermittent fasting may reinforce distorted self-image or dangerous behaviors in some people. Cavan Images/Getty Images
  • New research suggests that intermittent fasting, while a popular eating trend, may lead to dangerous eating behaviors in some young people.
  • Experts say fasting can reinforce a distorted self-image or compulsive behaviors in vulnerable people.
  • They also say more research is needed to confirm whether this dietary approach is actually a healthy way to control weight.

Intermittent fasting (IF) has been popularized for its supposed health benefits, which are supported by some to research.

But new findings published in Eating behaviors from the University of Toronto have linked intermittent fasting to eating disorders and potentially dangerous compulsive behaviors.

According to Dr. Jessica Folek, director of bariatric surgery at Long Island Jewish Forest Hills, which is part of Northwell Health in New York, IF is a diet characterized by cycles of fasting and time-restricted eating.

“These include time-restricted feeding,” she told Healthline.

Examples of SI include 16/8, where you fast for 16 hours and eat during an 8 hour window, 14/10, which means fast for 14 hours and eat between a 10 hour window, and other variations, explained Folek.

“FI has become very popular and some studies have shown FI to be effective for weight loss,” she said.

“However, there is a lack of long-term studies and studies with conflicting results.

The University of Toronto study analyzed data from nearly 3,000 adolescents and young adults originally collected by the Canadian Adolescent Health Behavior Study.

Researchers found an association between IF and all disordered eating behaviors in women.

“This includes binge eating, as well as compensatory behaviors like vomiting and compulsive exercise,” lead study author Kyle T. Ganson, PhD, MSW, assistant professor in the Faculty of Factor-Inwentash Social Work Research from the University of Toronto.

“For men, those who tried the diet routine were also more likely to report compulsive exercise.”

Ganson added that he was not surprised by the results.

“Since we know that dietary restriction/restriction is a major risk factor for eating disorders, we hypothesized that IF, which is in many ways a more regulated practice of dietary restriction/restriction , would be too,” he said.

Ganson and his team found that the prevalence of intermittent fasting behaviors among teens and young adults was significant.

The results indicate that 38% of men, 47% of women, and just over half of gender non-conforming or transgender people said they had practiced IF in the past 12 months.

Participants also reported fasting for an average of 100 days over the past 12 months.

“Additionally, it was concerning that FI was associated with many dangerous behaviors in young women, including compulsive exercise, laxative use, and vomiting,” Ganson said.

Dr. Timothy B. Sullivan, chair of psychiatry and behavioral sciences at Staten Island University Hospital in New York, told Healthline that fasting can produce a temporary state of pleasure or relief from distress.

“Similar to self-harm behavior, fasting in vulnerable people may be reinforced via reward pathways in the brain, as the behavior blunts anxiety or other unpleasant moods,” he said.

Sullivan added that fasting could reinforce a distorted self-image or other “compulsive thoughts and behaviors” in those who feel they need to lose weight to achieve social acceptance.

He pointed out that young people are already at an increased risk of developing an eating disorder.

“Studies show that teens and young adults, as a group, are at increased risk for eating disorders,” Sullivan said.

“Women, for reasons that are not fully understood, are at increased risk compared to men, and transgender people are at particularly increased risk.”

Folk said some studies show IF has benefits that include “improved gut hormone levels, especially reduced insulin levels, which lowers our risk of insulin resistance and diabetes, decreased markers of inflammation and a decrease in visceral fat.

She added that more rigorous studies are needed to validate these findings, and recent research has not shown benefits of using IF.

“A recent randomized controlled trial did not demonstrate superior weight loss compared to traditional calorie restriction diets,” she confirmed.

According to Folek, this study demonstrated a significant and concerning decrease in muscle mass compared to traditional diets.

“Typically, about 20 to 30 percent of the weight lost is lean body mass,” she said.

“It’s concerning because it could dramatically reduce the metabolic rate, which also led to weight gain down the road.”

“The treatment of eating disorders is complex and usually managed by an interdisciplinary team in a specialized program or clinic,” Sullivan said.

He added that treatment can include medication, but always includes counseling and behavioral interventions that can reduce the “often unintended environmental reinforcement of these harmful behaviors.”

According to Sullivan, a balanced diet, healthy physical activity, maintaining supportive social networks, and addressing mood disorders, whether anxiety or depression, will all help reduce the risk of a person develops an eating disorder.

Ganson said IF shouldn’t be considered a “benign dietary trend.” Instead, he explained that it was linked to an increased risk of eating disorder-related attitudes and behaviors.

Ganson noted that healthcare professionals should be aware of these potentially correlated behaviors and “understand that contemporary dietary trends, like IF, are commonly discussed among young people, especially on social media.”

He advised conducting more comprehensive assessments among young people regarding eating practices and providing them with appropriate counseling where necessary.

“This study underscores that trendy behavioral practices, like intermittent fasting, that grow rapidly and gain traction through social media can produce unintended adverse effects,” Sullivan said.

He stressed that rapid intervention is needed to reduce the risks associated with this and other trends.

“The only way to avoid serious adverse effects is to be alert to such trends and to intervene quickly when we see changing health risks,” he said.

Despite its popularity and purported health benefits, a new study has found that intermittent fasting can lead to unhealthy and even dangerous behaviors in teens and young adults.

Some people may be particularly vulnerable to a distorted self-image and to dangerous and compulsive behaviors.

Although the study results are concerning, more research is still needed to confirm whether intermittent fasting can support healthy weight management in young people.


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