Healthcare professionals, including pediatricians, clinical psychologists, nutritionists, and eating-disorder specialists, are trying to halt an Australian study looking at the effects of an intermittent fasting diet on adolescents.
They say “Fast Track to Health,” a year-long research project at Monash Children’s Hospital in Melbourne and The Children’s Hospital at Westmead in Sydney, is unethical, because restrictive diets increase the likelihood of future eating disorders, especially for teenagers.
While intermittent fasting has been touted as a buzzy bio-hack, especially among the Soylent-swilling Silicone Valley set, the few studies that exist on the subject have found that it isn’t more effective than straightforward calorie reduction for weight loss. And public health experts say it could be far more dangerous.
Louise Adams, a clinical psychologist in Australia, submitted a complaint, co-signed by 28 other health experts from Australia and the US, to the Human Research Ethics Committee (HREC) at Sydney Children’s Hospital, the body that approved the study. She also started a Change.org petition calling to halt the study. Adams says that the study illustrates the harmful stigma surrounding body size. “The world would prefer people to be sick with an eating disorder than to be in a larger body,” says Adams. “That is weight bias.”
Recent research has shown that dieting is one of the major precursors to developing an eating disorder, and that teenagers who diet, skip meals, and otherwise reduce caloric intake are more likely to develop a disordered eating behaviors and to be overweight than their non-dieting peers. ”We know clinically that restriction leads to overeating,” says Adams.
What are the dangers of dieting?
A 1999 study of 2,000 Australian teenagers found that girls who dieted were five times more likely than their non-dieting peers to develop eating disorders, and those who followed very extreme diets were 18 times more likely. Dieting was the single biggest predictor of developing an eating disorder. While the difference between extreme and moderate dieting is somewhat subjective, a 2017 study of adults comparing intermittent fasting to straightforward caloric reduction, 38% of the fasting group dropped out of the study, as opposed to 29% for calorie restriction group, suggesting that fasting is harder to stick with, and based on this criteria, arguably more extreme.
Adams and her co-signers question the need to study intermittent fasting and weight loss in adolescents since research done on adults to date has shown it to be no more effective than basic calorie restriction, which itself is rarely effective in the long term. Most studies of children and body weight tend to look at behavioral changes—screen-time reduction, better access to healthy foods, and the social components of food and health through the lens of families, rather than comparing different strategies for calorie restriction.
What we know about weight-neutral interventions
Adams points out that weight-neutral interventions, which have the goal of improving physical and mental wellbeing without consideration for the number on the scale, have been shown to be effective in teenagers, without the risks of dietary restrictions. So why submit kids to those risks, just to see which dietary restriction works the best? “We should look at stuff like intuitive eating, helping kids to let go of food rules, doing a lot of work on developing a healthy body image and noticing weight bias and weight stigma,” she says. “Helping kids develop a relaxed and enjoyable relationship with food…and with moving their bodies.”
In the complaint letter, Adams points to the link between weight stigma and physical and psychological health, and calls for weight-neutral approaches to health. She also notes that the American Academy of Pediatrics’ recommended treatment for obesity focuses on family-based behavior modification—providing access to healthy foods, limiting screen time, and encouraging physical activity. In those guidelines, the AAP writes that, “understanding that poor body image can lead to an ED [eating disorder], parents should avoid comments about body weight and discourage dieting efforts that may inadvertently result in EDs and body dissatisfaction.”
Another major concern about the study is that the risks of significant dietary restriction have not been clearly outlined for families. The consent form for parents reads, “We do not expect any side effects or risks associated with this study. If the study makes your child feel upset, you or your child may stop the study at any time.”
How does intermittent fasting work in this context?
Fast Track to Health aims to enroll 186 adolescents ages 13-17 with a BMI of 30 or higher. For the first month, all the children will consume 700-800 calories a day. Then, for the remainder of the year, they’ll be split into two groups. One will follow a “Modified Alternated Day Fasting” diet for three non-consecutive days a week (600-700 calories each day), and a “standard healthy diet” based on the Australian Dietary Guidelines during the other four days of each week. A second group will follows a low-calorie diet (1,450-1,900 calories) every day. The AAP estimates average adolescent calorie needs to be between 2,200-2,800 calories a day. The AU$1.2 million ($860,000) study is funded by Australia’s National Health and Medical Research Council, a government health organization.
In its response to the complaint, the HREC found that the study meets Australia’s guidelines for research merit and integrity. However, it did require the research team to strengthen its risk-management plan, including “improving communication with participants and their families regarding the risks associated with eating disorders,” and adding closer eating-disorder monitoring to the study.
In response to a request for comment, a spokesperson from the Children’s Hospital at Westmead sent a letter (pdf) stating that “significant precautions have been taken to identify any risks of harm to any participant during the trial and appropriate steps are in place to manage and mitigate these risks.” It also acknowledged that the diet would not be appropriate for teenagers without close medical supervision. “This type of eating plan should only be undertaken under close clinical supervision of a multi-disciplinary team in a tertiary hospital setting and is not intended as general advice to the public,” the letter stated.