When dieting gets dangerous
Let me introduce you to two hypothetical teens: Teen A and Teen B. Both teens go on diets. It could mean they want to lose a few pounds, it could be they are trying to “eat healthy” or be better at their sport. Regardless of why, they start cutting back on the amount and variety that they’re eating. Most people will be like Teen A- maybe they’ll stick with it, maybe they won’t. They might get a little odd about food, but all in all, they’re fine. Teen B, however, isn’t fine. First there’s the attempt at weight loss or eating less, then there’s a full-blown eating disorder.
Exactly why an individual develops an ED is going to vary from person to person, as each individual will have different contributions of genetic and environmental factors involved in their disorder. There’s the saying that “Most EDs begin with a diet.” Which I think should be amended to “Most EDs begin with a negative energy balance,” but that’s not nearly as catchy. There’s kind of a corollary to that: most diets don’t lead to EDs. So what factors make someone vulnerable to an eating disorder after a period of negative energy balance?
There’s genetics, sure, but no one knows exactly what genes are tugging on what behaviors. Researchers wanted to know if there’s a way to predict which dieting young people are at higher risk of developing an ED. It turns out there is. The answer appears to be in understanding a person’s motivation for their food restriction. If a person is motivated by negative affect, which includes symptoms of anxiety, depression, guilt, and anger, then they are much more likely to develop an ED than “normal” dieters.
Beware the negative affect
Researchers in Finland had asked the same question I had: what factors make some adolescents more likely to develop an ED after dieting (term used loosely) than others? They looked at not only differences in dieting behaviors but also (more importantly to their findings) psychological variables. To answer this question, they first gathered baseline data on 595 adolescents currently in the 9th grade in one area of Finland. All of these teens (average age: 15) filled out questionnaires about current and past mental health, health behaviors, life circumstances, and brief questions about dieting and EDs (Isomaa et al., 2010).
128 teens endorsed both dieting and fulfilled one or more of any of the DSM-IV criteria for EDs, and were called back for a longer in-person interview. Of the 113 teens who returned, 81 were classified as “confirmed dieters.” The researchers were able to conduct follow-up interviews with 65 of the teens. They researchers did not provide data on the number of teens who dieted without fulfilling at least one DSM-IV eating disorder criterion, nor did they follow up on these people, which is a weakness of the study (they are already selecting for higher rates of psychopathology, which could influence the significance of their findings).
With all of these interviews, the researchers were able to create four mutually exclusive groups of dieters, below (the descriptions are copied directly from the paper):
Overweight dieters (n=12) dieted to lose weight to avoid associated adverse health consequences of their overweight. They appeared to have a sensible approach to means of dieting and exercise. All overweight dieters had an age-adjusted BMI ≥25 at the onset of dieting.
Depressed dieters (n=33) dieted because of depressed mood and emotional problems, which they believed would be resolved by losing weight and obtaining a slim ﬁgure. The means of dieting varied among the depressed dieters, but approximately two-thirds used meal-skipping, purging or intense exercise to regulate caloric intake and expenditure.
Feeling fat dieters (n=8) could not give any other explanation for their dieting than a diffuse feeling of being fat, even though objectively being normal or underweight. They usually dieted by skipping meals, eating very little or exercising intensely.
The description of the “depressed dieter” resonated with me on a personal level, as that was my motivation for eating less and exercising more when my ED began in earnest: I thought it might make me less depressed if I lost weight.
The last two of these groups had higher levels of depression and anxiety, as well as lower self esteem, when compared to vanity and overweight dieters. Based on this, the researchers divided these four groups into two broader categories: vanity and overweight dieters were considered low risk dieters, whereas depressed and feeling fat dieters were high risk.
These classifications were confirmed at the three year follow-up. In the low-risk dieters group, five people (16.8%) developed a subclinical ED and only one person (3.3%) developed a full-blown eating disorder. In contrast, 10 people (28.6%) in the high risk group had developed a subclinical ED at follow-up, and 19 (54.3%) met the full DSM-IV criteria for an eating disorder. The differences were statistically significant even when controlling for known ED risk factors like depression and self-esteem. Dieters in the high risk group were 15 times more likely to develop an eating disorder. That’s a HUGE risk factor.
The authors conclude:
The ﬁndings have clear clinical implications, since asking adolescents about their reasons for dieting is a task manageable for people who are in every day contact with adolescents, for example parents, teachers, youth workers and school health personnel. Adolescents who start to diet because of emotional problems or a diffuse feeling of being fat should be closely monitored. The study also suggests that merely dieting among adolescents, in most cases, is quite harmless, if not accompanied by depressed mood.
Although I don’t agree that people who are overweight and dieting should be automatically lumped into the low risk group (if they have intense body image distress or depressed mood, they are clearly high risk whatever their weight is), these results are really important and interesting because they indicate a way to try and tell whether a dieting teen might be moving along a high-risk path towards developing an ED or whether it’s a slightly more benign practice that might not have any majorly serious consequences–though if it were my kid, I would discourage dieting because it’s pointless, not to mention the genetic risk for EDs that they would have. Clearly, if your family tree has eating disorders in them, especially in close relatives like parents, grandparents, aunts, cousins, siblings, etc, then dieting should be actively discouraged.