Eating Disorders

Unintentional Weight Loss as a Trigger for Anorexia.

Contrary to popular belief, weight loss leading to anorexia nervosa (AN) does always start intentionally and may follow an illness. Some of the biggest misunderstandings about anorexia nervosa center around it being an intentional illness and related to vanity.

Paper on Unintentional Onset of Anorexia

A paper by Brandenburg and Andersen in 2007 entitled Unintentional Onset of Anorexia details case histories of 5 individuals who were deemed to have anorexia precipitated by “unintended weight loss” as opposed to the “more typical onset following intentional dieting.” In the paper, the authors reported that a retrospective review of 66 consecutive outpatient evaluations at an eating disorder clinic revealed 5 (7.6%) cases of “inadvertent onset AN” (Anorexia Nervosa). They stated that this finding “calls into question whether dieting is a necessary precedent for AN; and suggests some individuals, perhaps genetically or psychosocially vulnerable, may need only weight loss from any source to result in clinical AN.”

Brandenberg and Andersen went on to say, “It was only after the unintended weight loss had occurred that the patient developed the desire to lose more weight or maintain the unsought lower weight.” Of the five cases described in the paper, the sources of weight loss included parasitic infection, medication side effects, post-surgical weight loss, and bereavement.

Negative Energy Balance By Any Cause is Bad For People with Genetic Vulnerability to Anorexia

It is now believed that people with a genetic vulnerability to anorexia respond aberrantly to negative energy balance, allowing anorexia to develop. While it is recognized that the source of this energy imbalance could be intentional or unintentional, Brandenburg and Andersen is the only research paper I have been able to find on the topic.

In my practice, I have seen a teen who forgot to eat over a high school exam period. Only after the initial weight loss, she grew anxious about her weight and started more deliberately restricting. In today’s fatphobic society, the most common source of energy imbalance is likely dieting, but this is clearly not the only path.

Parent Survey on Causes of Weight Loss That Led to Anorexia

Parents on the Around the Dinner Table forum, a moderated online forum for parents and caregivers of eating disorder patients, pondered this same issue. They completed a poll: “What caused your child’s weight loss, precipitating AN?” The results break down as follows:

Cause Cases Percent
Dieting to lose weight 77              22%
Trying to eat healthy 90              31%
Overtraining for athletics 38              13%
Fasting for religious event / reason 2                0%
Becoming vegetarian / vegan 12                4%
Illness 18                6%
Other, unknown 44              15%



Overall, 6% of cases were reported as due to illness. This finding is remarkably similar to that of Brandenberg and Andersen.

Comments by FEAST Parents

Furthermore, some of the comments on the FEAST survey relating to the “inadvertent onsets” included:

  • “My daughter had pneumonia and lost at least 10 pounds. She gained it back but it became a battle after that to get the weight back off again. Daughter said at some point that weight loss was completely out of her control.”
  • “World Vision’s 30-Hour Famine to raise money for starving children in the Third World. Within a week she had decided to lose 30 pounds and off she went.”
  • “My daughter started to increase exercise/training for state selection in her chosen sport. Two months into daughter’s increase in her training regime she had her wisdom teeth removed and could not eat solid food for 3 weeks….And our story begins!”

Mononucleosis was mentioned. Physical growth without commensurate weight gain also rang true for several parents. At the NEDA conference in San Diego, a woman shared that her daughter’s anorexia developed after weight loss following 15 months of chemotherapy at age 11.

Brandenburg and Andersen concluded, “Physicians in all specialties should be aware that weight loss in predisposed individuals may trigger anorexia nervosa.” However, this is the only paper I have found on the subject, and it is behind a paywall (not accessible for free to the community). The message is not reaching its intended audience. As others have highlighted, it’s important to draw attention to this issue to dispel the widespread belief that eating disorders “always” start out as a desire to be thin. It’s also important to protect teens from weight loss by any cause.

Since anorexia nervosa is an illness and not a choice, perhaps a more apt title would have been “Unintentional Weight Loss as a Trigger for Anorexia.”

Weight Gain as a Priority for Recovery

These examples also highlight why weight restoration is a priority for all people with anorexia. In our Family-Based Treatment approach, we aim to set recovery weights that will facilitate a full recovery.

Get Help for All Eating Disorders in California

Help for anorexia and other eating disorders is just a call, email, or click away. Contact EDTLA to get started.

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