The allure of fad diets, and why they fail

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Janet Chrzan’s work falls at the intersection of nutrition and anthropology. “I’m interested in how our social worlds channel food choices that contribute to health outcomes,” says Chrzan, an adjunct assistant professor in Penn’s School of Nursing and in the Department of Anthropology in the School of Arts & Sciences.

In the past, she’s studied and written about subjects including organic farming and alcohol consumption. Recently, she published a book about fad diets with colleague and psychology professor Kima Cargill from the University of Washington, Tacoma. “These diets aren’t really about the food,” Chrzan says. “They’re about identity, status, control, and transformation. They have power because we believe they will fulfill our desires for self-improvement.”

Following is an excerpt from that book, “Anxious Eaters: Why We Fall for Fad Diets,” published in August 2022 by Columbia University Press.

You’ve heard of them and may have one or more friends on them; maybe you’re on one yourself. With these diets, you sharply limit certain foods because you want to lose weight, avoid illness, reset your body, eat a biologically ideal diet for our species, or “live your best life.” They come and go, gaining and losing popularity in a somewhat predictable social cycle and changing names—if not practices—as new advocates rediscover and capitalize on their re-creation of the new-old craze. One decade might abjure fats, the next lives in fear of carbohydrates.

Cookbooks pop up in quick and easy abundance to offer simple, family-friendly recipes that supposedly eliminate the forbidden food category (these same cookbooks will populate the shelves of charity thrift stores in a few years). Celebrities and health gurus endorse the diet, and it becomes the only way to demonstrate how much you value health and well-being to your friends, family, and Instagram followers.

These are the diets that define fad diets: they promise easy solutions and rapid fat loss only if you remove an entire category of food from your diet. Why is this particular type of fad diet so appealing?

Food removal diets are often branded and ask the dieter to spend money on special foods, membership in an organization, or the services of a professional nutritionist, personal trainer, or coach. Paradoxically, these food removal diets often wind up adding foods, albeit special ones intended to replace the foods that are supposed to be removed.

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These diets appeal to a uniquely American practice of shopping to solve problems, following a widely held belief that consumption solves, rather than creates, problems. It is the commodification of inadequacy—the ways in which brands and the consumer marketplace remind you of all the ways you could be better. We suspect that buying things to solve problems creates a sense of agency among dieters: Purchasing special foods makes them feel more efficacious than if they just ate a little bit less all the time.

Shopping, spending, and eating are all part of a faith in consumption that influences our culture, but our attempts to solve the problem of being overweight through more consumption mistakes the disease for its cure, perpetuating a confusing pursuit of good health in a world of consumer goods. Even one of the oldest and most successful diets, Weight Watchers, relied on membership subscriptions well before its branded foods and online services developed.

In the 1960s a woman named Jean Nidetch, after losing significant weight herself, had the idea to create a support group with attendance fees for people who wanted to lose weight (what became Weight Watchers). Scoffers said, “Oh please. No one’s going to pay money to lose weight.” Weight Watchers proved them wrong.

Chrzan has enjoyed hundreds of conversations with people on fad diets, and most of those diets eliminate one or more foods rather than decrease the amount of food eaten. People say they adopt the diets to decrease caloric intake, reset metabolism, restore health, or simply lose weight quickly. These diets are so popular that eliminating a food type may be the archetypal diet in the minds of Americans, rather than, for instance, eating less or less frequently or replacing high-calorie foods like fatty snacks with low-calorie options like fresh fruit.

It is even possible that the concept of “food reduction” has come to mean “reduction of a food group (or macronutrient)” rather than “reduction of the overall amount of food.” Two examples stand out as typical and interesting because the people involved were self-aware and conflicted about the diets—Atkins and Whole30—and their efficacy. The former diet eliminates most carbohydrates, and the latter eliminates most carbs and many fats, gluten, all sugars, and alcohol, promising a fast health reset. Both tout their capacity to cause rapid weight loss.

Once when Chrzan was at a pet store, the clerk recommended an all-protein, no-carbohydrate food as the best option for cats: “This food has no carbs, which is good. We shouldn’t be eating any carbs, and neither should our cats. They are very bad for us.” Janet responded that while cats were obligate carnivores and didn’t require large amounts of carbohydrates, humans were omnivores and absolutely needed to eat a balanced diet with differing forms of carbohydrates. The clerk asked why “everyone knows” that carbs are bad if they aren’t, and then asked what Chrzan meant by different kinds of carbs.

A few minutes later, after discussing simple and complex carbohydrate biochemistry, the clerk said his girlfriend was often on a diet and that most required cutting out carbs. She did Atkins for a while, and now she’s on and off Whole30. He admitted that it made dinner much less enjoyable: “You know, I do like my pasta and the occasional pizza, and if she can’t share with me, it’s not a real meal.” And then he said that she never seemed to lose weight on the diets, that she’d take it off, and then as soon as she stopped the diet—or went to a new one—the weight would all come back, plus more. She’d look for the next diet, one that was even more restrictive, something that was sure to work because it made sure she couldn’t eat “all the bad foods.”

Chrzan then talked about how the body physically compensates with weight gain after experiencing a starvation episode and why and how avoiding carbs causes rapid weight loss—and rapid weight gain after. The clerk eventually agreed that what works for a carnivore probably doesn’t work for a species that evolved from fruit-eating primates.

The second example is from a conversation with friends who were anticipating “doing the Whole30” as part of a sober January, to “clean the body and lose the holiday weight.” They explained that they always went on Whole30 in January, to “get rid of the toxins” from the holiday excess. But, they said, “It’s really hard, because we get together with friends every week for dinner and so it’s difficult to have a shared meal. Sometimes we’re all on Whole30 and so we can agree on the food, but we really enjoy having a glass of wine; we don’t get drunk or anything, just it’s nice to have a relaxing evening. And the food, well, that gets boring too, doesn’t it? I mean, there are lots of recipes out there for Whole30 meals, but it’s just missing something after a while, isn’t it?” 

Chrzan asked why they adopted Whole30 if it wasn’t pleasant, and the response was “Well, it’s the best way to lose it, isn’t it? You just avoid all the bad foods, and it gets rid of the inflammation and the toxins from the body. But the food is really hard to keep doing; you really start to miss having a pasta dinner or some good sourdough bread. But the diet’s really good for you, so we do it for a month to get rid of the Christmas weight.”

She asked if they lost weight on the diet, and they told her they weren’t sure they did, “but that’s not all it’s about; it’s about resetting the body, getting a good clean start to the year, getting rid of all the toxins—oh, but then in February we sometimes eat and drink enough to make up for January!” Planning a month of sobriety and conscientious eating is a good idea—many cultures embrace fasting to encourage health, reflection, and renewal—but this example demonstrates that embracing a diet that makes socializing difficult could be counterproductive.

Several themes stand out from these conversations.

One is that the diets might not work and may also cause compensatory behavioral overindulgence leading to weight gain. Two, they are difficult because people miss certain foods. Three, they are difficult because they disrupt valued personal and social habits. Four, they make socializing difficult or more complicated because people can’t share food easily. And five, they are perceived to be difficult by their users and are unpleasant as an everyday food regime.

They disrupt commensality and food habits enough that maintaining the diet becomes complicated and difficult. Furthermore, people justify their use with a variety of reasons that might not be accurate, because removal of toxins or a perceived decrease in inflammation isn’t necessarily something the diets accomplish.

We are left with the question of why people do them if they are difficult and unpleasant, and after many conversations, Chrzan suspects that people justify their adoption because they are unpleasant and difficult. Indeed, she has come to suspect that the difficulty is linked to a mental perception of efficacy and that sacrifices might equate with a magical thinking that such great unpleasantness will produce correspondingly profound wished-for outcomes. Like Benjamin Rush’s adoption of heroic medicine, because the cure is so extreme, shocking, and painful, it has to result in a similarly robust positive outcome.

Kima once worked with a couple who fell on and off the diet and exercise wagon with regularity. When they were on, the regimen teetered on masochism. They drank no alcohol and ate only poached chicken breasts, steamed broccoli, and other bland foods that they perceived as “healthy.” They paid hundreds of dollars per month to a boutique gym with a personal trainer and took “boot camp” classes whose routines sounded byzantine. They described running through tires, climbing a rope to ring a bell, coming down a zip line, and then doing a lot of jumping jacks and crunches. Because they weren’t used to eating or exercising this way, the diet resulted in boredom and noncompliance within a couple of weeks, and the exercise program resulted in injuries, soreness, and exhaustion within a month.

Once they fell off the wagon, they ate most of their food from fast food chains, drank both cocktails and wine nightly, and stopped exercising completely. Of course, the weight came back quickly, along with a crushing sense of defeat. What was striking was the difficulty they had achieving something in between these two polarities. Kima could never convince them to go on a daily walk in their neighborhood or enjoy a simple, tasty dinner of chili and one or two beers. They dismissed this middle ground because it wouldn’t be efficacious enough, and instead repeatedly opted for episodes of an extreme but unsustainable lifestyle that mirrored what they saw on blogs and social media feeds.

We have heard, again and again, that people simply can’t continue on fad diets, that they fail because they are abandoned. Something “just doesn’t seem right” with their meals, and they’re hard to maintain for a long time. That might be why so many of the carb-reduction diets tout a 14- or 30-day plan and then allow users to gradually increase carbohydrates.

But we also suspect that they fail because they interfere with the concept of the meal and with commensality, two deeply embedded cultural practices that define eating for many people. After all, people eat meals (not single foods) even though they often write and think about food as some type of nutrient package, or with some other individualized classification system that separates food from the everyday lived practice of eating. Leaving out a macronutrient may become difficult over time because our brains, cultures, and dining expectations tell us that our meal must include carbohydrates or fat to be conceptually complete.

Our cultures train us to eat a certain way, and if we do not, we feel that something is vaguely wrong. Similarly, most of us also value eating together, and our preferred mental image of “how to eat” involves food sharing. After all, we valorize the family meal, and people treasure eating out with friends. Many of our cultural rituals require celebrating together over a table groaning with special foods.

The idea of eating together is baked into our understanding of how to feed ourselves, and so adopting a diet that makes it difficult to enjoy a meal with the people we care about makes that diet much less attractive over time. We suspect that these two cultural constructs—the structure of the meal and eating together—make the practice of these diets difficult and likely to be abandoned.

Janet Chrzan is an adjunct assistant professor in Penn’s School of Nursing and in the Department of Anthropology in the School of Arts & Sciences. Kima Cargill is a professor in the Social, Behavioral, and Human Sciences division of the School of Interdisciplinary Arts and Sciences at the University of Washington, Tacoma. The text above was excerpted from their book “Anxious Eaters: Why We Fall for Fad Diets” ©2022 Columbia University Press. Used by arrangement with the publisher. All rights reserved.