One of the telltale signs of an eating disorder is a change in someone’s eating habits. But changing your eating habits is also the defining attribute of going on a diet—so how can you tell the two apart? The answer is nuanced, especially because the worlds of dieting, disordered eating, and eating disorders have a fair amount of overlap. Read on to learn the difference between a diet and an eating disorder, whether the former can cause the latter, and when to be concerned.

The basics about diets and eating disorders

First, let’s define the terms. While the word “diet” can refer simply to what a person eats, here we’re talking about weight loss diets. In that context, a diet can be defined as an eating plan in which someone eats less food, or only particular types of food, because they want to become thinner or lose weight for stated health or “wellness” reasons.

Eating disorders, on the other hand, are mental illnesses characterized by severe and persistent disturbances in eating behaviors, accompanied by distressing thoughts and emotions. Eating disorders are disabling and deadly disorders that have serious consequences on physical, psychological, and emotional health and disrupt a person’s ability to go about their life. There are several different types of eating disorders, including anorexia, bulimia, binge eating disorder, ARFID, and OSFED.

Unfortunately, dieting is extremely common. According to research, some 17.1% of American adults are on a diet on any given day, and half of adult Americans attempted to lose weight within the past year (which almost always involves dieting). Eating disorders, on the other hand, are less prevalent. About 9% of Americans will have an eating disorder at some point in their lifetime, and about 5.5 million will develop one this year.

So while dieting and eating disorders have similarities—both involve changes in food habits and a focus on making one’s body smaller—clearly not everyone on a diet has an eating disorder. Let’s take a look at the differences.

Telling apart a diet from an eating disorder

Telling the difference between a diet and an eating disorder can be tricky, especially in the context of diet culture, which tends to praise and normalize disordered behaviors, like fasting or cutting out entire food groups. However, there are specific things you can look for that can signal it’s not “just” a diet.

Some of the primary differences between a diet and an eating disorder include:

• How long it lasts: Generally, people go on diets for a finite amount of time. Someone may go on a diet ahead of an event (like a vacation or a wedding, for instance), or in order to reach a certain weight, and then go back to more normal eating afterward. Eating disorders have no natural end; people will continue to engage in their disordered behaviors until they get treatment.
• How it impacts other areas of a person’s life: “Dieting becomes an eating disorder when it’s associated with significant impairment in physical, emotional, occupational, or social domains,” explains Cara Bohon, PhD, Senior Vice President of Clinical Programs at Equip. Eating disorders can hurt relationships, negatively affect performance at school or work, and make it impossible to keep up with daily responsibilities.
• How much mental real estate it occupies: “A shift in thought patterns is one of the first red flags I often see,” says Christina Fattore, a registered dietitian and Clinical Partnerships Representative at Equip. When compulsive thoughts about food, exercise, or body size and shape begin to take up most of a person's brain space, it’s time to be concerned.
• How important it is: Diets are pretty straightforward: they’re about following food rules and achieving a certain weight, and there is no deeper meaning. Eating disorders may look similar on the surface, but they become about much, much more. For someone with an eating disorder, there are extremely high stakes attached to the rules of their disease. If they “slip up” or ignore their eating disorder voice, they feel intense distress.
• Whether or not it feels like a choice: In general, going on a diet is a choice someone makes, and they can choose to stop when it no longer serves them. An eating disorder is not a choice, and someone can’t just decide to stop having an eating disorder. “Dieting has solidified its place in our society as a desirable lifestyle choice. However, I think it’s important to remember a diet is just that: a choice,” says Fattore. “With an eating disorder, the disorder itself is in the driver’s seat, not the other way around.”

These differences help to illustrate the different ways that diets and eating disorders affect a person, but they can be difficult to quantify or even to see at all, especially if you’re concerned about a loved one. Below are some more easily identifiable red flags:

• An extreme rigidity around food rules. “Eating disorders don’t make space for ‘cheat meals’ or ‘days off,” explains Fattore.
• Preoccupation with body size or shape. This might look like body checking, frequently weighing oneself, or comparing one’s body with other people’s bodies.
• A fixation on calorie counts and nutrition labels. This can also show up in behaviors like measuring and weighing food, and a need to be extremely precise about the quantities or kinds of food eaten.
• Mood shifts associated with insufficient nourishment. “Think about the term ‘hangry,’” says Bohon.
• Physical ailments that appear to be related to a person’s restrictive eating. This could include fatigue, hair loss, brittle nails, always being cold, or getting sick frequently.
• Social withdrawal. People with eating disorders tend to avoid plans that involve food, or turn down invitations in order to exercise. “Dodging situations that would require one to practice food flexibility is an indication that we’re veering into dangerous territory,” says Fattore.
• Other disordered weight loss behaviors in addition to the diet. This could include self-induced vomiting or misuse of laxatives.

If these signs resonate with you, taking our interactive eating disorder screener could be a helpful next step.

Can a diet cause an eating disorder?

While diets and eating disorders are decidedly different from one another, one can lead to the other. This doesn’t mean that diets cause eating disorders (otherwise, everyone on a diet would develop an eating disorder, and that’s not what we see), but it does increase risk.

“For many years, it was consistently shown in research that dieting was a risk factor for the development of eating disorders,” says Bohon. She cites research from the early 2000s that found that attempts to restrain eating were “robust predictors” of the onset of eating disorders—findings that were replicated over the following decades—as well as more recent studies finding that tracking food with apps, counting calories, and self-weighing all increase eating disorder symptoms. Research has also found that teenage dieting is what usually precedes the onset of bulimia and anorexia, and prospective studies have associated dieting with at least a fivefold increase of developing an eating disorder.

Bohon does point out that some findings call this association into question. Some researchers, she says, suggest that dieting for weight loss doesn’t increase eating disorder risk, citing evidence that weight loss programs result in reductions of eating disorder symptoms. But there are flaws in making this conclusion. “This interpretation of the evidence is short-sighted,” Bohon says. “As eating is controlled via dieting, concerns about shape or weight or eating are tempered. But when the dieting stops, the concerns elevate. Given that most weight loss efforts fail—weight is either not lost or regained the following year—any reductions in eating disorder symptoms would be expected to be temporary.”

For some people, dieting itself can be a trigger for an eating disorder—likely because a negative energy balance, or eating fewer calories than you burn, can trigger an eating disorder in people predisposed to developing one. For others, dieting might appear to lessen disordered thoughts or behaviors, but that relief is short-lived: the relief comes from the fact that a person’s body more closely matches society’s thin ideal, and when the weight inevitably comes back, so do the disordered behaviors.

It’s also worth calling out that even for people who won’t go on to develop an eating disorder, dieting can have negative consequences. Studies have found that dieting can lead to nutritional deficiencies, menstrual irregularity, osteopenia and osteoporosis, and stunted growth in kids and teens, among other issues. Research also suggests that chronic dieting can lead to irritability, fatigue, distractibility, and binge eating. As one team of researchers put it, “our results showed that dieting may carry more risks than benefits as a means to lose weight.”

Is dieting inherently bad?

Ultimately, it’s up to each individual person to decide what food choices work best for them. For people with celiac disease, that means cutting out gluten; for those who are lactose intolerant, that means eliminating dairy; others might simply find that they feel better when they eat certain foods rather than others. In all of these cases, a person’s chosen diet wouldn’t be considered disordered.

But when it comes to diets designed specifically for weight loss, it’s a different story. As the research shows, dieting for weight loss purposes is rarely sustainable and increases your risk of developing an eating disorder, making it a lose-lose endeavor.

Fattore sums it up like this: “If ‘going on a diet’ means incorporating a higher volume of nutrient-dense foods, exercising in a way that’s mentally and physically rewarding, and engaging with food in a more mindful manner, then sure, dieting can be healthy,” she says. “But if a diet means depriving your body of necessary calories, cutting out entire food groups, or ignoring physical cues like hunger or exhaustion, then I don’t think we can ever truly classify dieting as healthy.”

Are you worried that your diet has gotten out of control?It could be an eating disorder.

Schedule a consultation