If you ever find yourself hopelessly lost at a Whole Foods, you’ve probably wandered the aisles and seen a dizzying array of ready-to-eat snack bars: Pro Bars, Clif Bars, Rx Bars, Luna Bars, Bobo’s Oat Bars. And the bar phenomenon is not limited to your local upscale organic food chain: According to a recent Outside Magazine piece, the market has absolutely exploded in recent years, with mainstays like Kind and Clif competing with upstart brands like Larabar and Zing to rake in an estimated $5 billion globally.

A casual observer of the bar market may conclude that these brands seem pretty interchangeable. But snack bar brands range widely in terms of ingredients and their target consumers: While companies like Clif Bar appear to be focused on catering to a more active clientele, brands like Kind appear to be catering to more of a #girlboss crowd. Kind’s Instagram features women with ombre hair and matte red lips sampling bars alongside matcha lattes. Yet almost all of these companies position their bars as healthy items for people who care about what they put in their bodies.

“Our tribe is knowledgeable about ingredients. They want to know exactly what they are eating,” says Shane Emmett, the co-founder of Health Warrior, which is best known for its chia seed bars. Although Emmett declined to share specific sales figures, he says that Health Warrior sells millions of bars per month and has reportedly grown considerably since the company started selling products in Whole Foods in 2012. “They work out four or more times a week, [they] are often on the go as parents, and (for whatever glorious reason) tend to have a dog.”

Dog ownership aside, it’s clear that people are buying snack bars because they think they’re good for them — but whether or not they actually are is, depending on who you ask, another story altogether.

Why are snack bars so popular?

It may seem like only recently people developed a taste for six-inch hunks of dried fruit and sorghum. But Outside writer Marc Peruzzi attributes the rise of bars to a number of factors, from millennials’ desire for more organic and wholesome ingredients to a heightened demand for on-the-go meal options, which he dubs “the snackification of the country.”

It seems to be true that the explosion of snack bars has in part arisen from the increasing demands of the US workplace, says Brett Klein, a dietician and co-founder of the nutrition counseling and wellness company the Wellthy Plate.

“There has been a large increase in the number of people snacking in the last 30 years as our dietary patterns have shifted and the number of hours we spend at work have increased,” Klein says. “This has created an increase in demand for quick, easy food options and the market has exploded to meet that demand.”

For this reason, many brands have marketed themselves as “meal replacement” bars, or more attractive alternatives to greasy takeout or #saddesksalads during a busy workday.

The emergence of specialized markets like the gluten free and vegan food product industries, as well as buzzy fad diets like keto and paleo, have also been boons for the bar industry, with brands like Bulletproof (famous for its keto-friendly, high-performance butter coffee) and Epic (which has cornered the market with its “meat strips,” featuring such high end ingredients as Wagyu beef and venison) dipping toes into the market.

“The gluten free product market increased 140% from 2014 to the projections for 2019,” says Klein. “The same can be said for keto products, which totaled $9 billion in 2018 and are projected to rise to over $12 billion in the next five years. … As new fad diets emerge, the snack market creates products to meet the demands of these new dietary parameters.”

Are bars healthy?

Within the nutrition and dietary community, this is a question subject to some debate. For the most part, the answer appears to boil down to: It depends. “I think there is a bit of a health halo around items like protein and snack bars,” Klein says. “Some protein bars are better options than others.  Many protein and snack bars are full of added sugars and can be of minimal nutritional quality, while others are a good option on the go.”

It’s crucial to note that just because something has health-conscious buzzwords like “keto” or “low-carb” or “superfood” on the label does not necessarily make it healthy. “One of the challenges of nutrition in general is we don’t work in nuance,” says dietitian Maya Feller. “We give things these blanket labels like ‘protein bars’ or ‘snack bars’ or ‘low-carb bars,” and while these labels sound healthy at face value, “the ingredients absolutely matter, and we don’t take that into consideration.”

One of the most common culprits is added sugar: an oft-repeated trope is that some snack bars are “candy bars in disguise” due to how much added sugar they contain. Indeed, Klein says you should look for a bar with less than 10 grams of sugar. (For what it’s worth, both Kind dark chocolate nut and sea salt bars and Health Warrior chia seed bars fall into this category, at five grams and three grams, respectively; chocolate chip Clif bars, by contrast, have a whopping 25 grams of sugar.)

You should also be aware of the source of the sugar, she says: “If it’s from a dried fruit, it’s a better choice than those with lots of added sugars from things like honey, agave, and rice syrup,” she says.

Additionally, be wary of more than 10 grams of added fiber. While brands often tout high fiber count to make their products appear more filling, many brands add ingredients such as chicory root fiber, which Klein says can cause added digestive distress for some. (Again, for what it’s worth, both Kind’s dark chocolate nut and sea salt bar and Health Warrior chia seed bars contain chicory root fiber.)

Overall, a good rule of thumb is to make sure the ingredients in the ingredient list are both pronounceable and identifiable. While some brands use the fact that their ingredients are recognizable as a marketing strategy, Klein says there’s some truth to it being a solid nutritional litmus test. For instance, if a label contains “any ingredients that end in ‘ol,’ such as sorbitol, mannitol, or erythritol,” that can be a sign that the bar may cause gastrointestinal distress, says Klein. It’s also best if the ingredient list is short and feature whole grains, fruit, or nuts at the top.

And don’t be suckered in by a brand’s claims that a bar contains a trendy “superfood,” especially if it’s unclear on the label exactly how much of a certain ingredient is in the product. “[Manufacturers] latch onto words they have health halos and are able to market them to people,” says Feller. “They can unknowingly or knowingly latch onto consumer confusion.”

This consumer confusion is, in part, what motivated Health Warrior to create its signature chia seed bars, as chia seeds have a reputation as a superfood packed with fiber and omega-3s. “We thought it was a ruse that most nutrition bars offered lots of empty calories and lacked micro-nutrients, plant-protein, and fiber from real foods,” Emmett says. “So we insisted on chia seeds being the main ingredient in our bars.”

The darker side of bars

The nutritional profile of protein bars aside, one of the main issues dietitians have with many brands is that they market their products as meal replacement bars, or substitutes for full and balanced meals.

“Protein bars can be a healthy and helpful food in certain scenarios,” says Torey Jones Armul, a spokesperson for the Academy of Nutrition and Dietetics. “Their protein content can provide satiety and keep you feeling full until your next meal. Because they’re portable and safe at room temperature, they’re a reasonable choice for people on-the-go or with limited access to fresh foods. They’re also helpful for athletes who need to replenish protein stores within a limited window of time.”

The trouble is that most people who regularly opt for protein bars — i.e., your average sedentary office workers looking to get in a quick breakfast or lunch between meetings — do not fall in this category. That’s why, “for most people, I recommend choosing fresh foods over bars when possible,” says Armul, simply because “whole, fresh foods tend to be higher in fiber, healthy fats and other important micronutrients.”

High-protein, healthy fat-laden snacks like eggs, raw nuts, and cottage cheese are likely a much better source of nutrients than most bars on the market, and will keep you fuller for longer.

Considering the fact that most people don’t want to offend their cubicle mates by whipping out a Tupperware container full of hardboiled eggs at breakfast, protein bars are seen as a solid and convenient meal replacement. But Feller says even higher-calorie bars likely won’t cut it as a meal replacement, leaving you hungry and eager to snack an hour or so later.

And this is an issue for those who are trying to manage their weight. “They’re marketed as ‘just grab it and go,’ and so many people just grab them and it’s a mindless activity, so they might not process they’ve eaten one,” Feller says. “An hour later, you’re having another meal, and you’ve been sitting at your desk all day.”

While this probably isn’t a terrible thing if it happens every once in a while, it’s not exactly a healthy long-term habit — and many brands lean into the perception that bars can serve as meal replacements in their marketing materials.

On its website, for instance, Health Warrior doesn’t explicitly say that its chia bars serve as a meal substitute, but it does use language to that effect, claiming that the bars “fill you up without weighing you down” — even though they are only about 100 calories, well below what the average man or woman needs for, say, breakfast.

When asked whether Health Warrior believes its bars are sufficient meal replacements, Emett said, “we don’t market or consider our bars ‘meal replacement’ because they don’t have enough calories to count as a ‘meal.’ However, you get a lot of nutrient bang for your buck”; because chia seeds are nutrient-dense and an excellent source of fiber, they can “make you feel fuller longer,” he added.

Perhaps more concerning, low-calorie meal replacement bars are sometimes used by those struggling with eating disorders as a way to manage their weight, largely because they are explicitly marketed as weight loss products.

“I do have some [eating disorder] patients who use snack bars in place of breakfast, and we work on it,” says Feller. “[I] have seen people who use these bars in place of food.” (It’s perhaps worth noting that Luna bars, a subdivision of Clif bars that are marketed exclusively for women, make appearances on pro-anorexia forums online.)

While brands themselves can’t be faulted for people using bars in less than healthy ways, the fact that some, like PROBar meal bars, are explicitly marketed as acceptable substitutes for full meals certainly raises some eyebrows in the nutrition community. “Eating disorders start in a psychological basis, and it’s more about the control, which I think is important to be said,” says Feller. “It’s about controlling your intake. And [relying on these bars is] very controlled.”

The future of the bar market

As bar brands attract more investors and high-end celebrity spokespeople (Kristaps Porzingis of the Knicks, for instance, is the face of Zing bars), it’s clear that the market is set to grow further. Bars are also migrating from the aisles of stores oriented toward natural foods like Whole Foods and Trader Joe’s into convenience stores and snack shops nationwide, meeting millennial consumers’ demand and edging out more blatantly unhealthy options like chips and chocolate bars.

“Younger people eat differently,” Errol Schweizer, the former vice president of grocery for Whole Foods, told Outside. “And whether they’re retail buyers or consumers, they buy accordingly.”  

Even behemoth snack companies that aren’t typically associated with the health sector are getting into the game, as evidenced by Health Warrior’s recent acquisition under undisclosed financial terms by Pepsi.

When asked about the unlikely marriage between a health food startup and a company that is primarily known for churning out soda and spicy cheese snacks, Emmett said: “We always wanted to partner — at the right time — with a food company that could help us put nutrition within reach of more people and that’s one of the things PepsiCo has been working hard to do for many years. We think they’re our perfect partner and look forward to doing big things together.”

While this bodes well for health food startup owners and CEOs, some nutritionists are worried that it bears ominous tidings for the future of the American diet, which is skewing much more towards snacking and less toward whole, balanced meals. “We really are a fast food nation, and bars are the ultimate answer to that,” Feller says. “It’s like, ‘Forget the fast food place. Here, have a bar.’”

And with the already staggering US obesity and diabetes rates only expected to rise further, the trend toward “snackification” may be cause for concern, regardless how many quote-unquote “healthier” snack options there are. “When we see this uptick of snack bars and convenience foods in certain areas,” Feller says, “then the question is: How sick are people going to become?”

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The first time Jenny Kutner decided to do Whole30, it was in October 2016, right before the presidential election. An elimination diet program created by a husband-and-wife team, Whole30 encourages people to give up alcohol, dairy, grains, legumes, and sugar for exactly 30 days. Toward the end of the 30 days, you’re supposed to slowly reintroduce these foods into your diet, to identify which ones work for you on a regular basis.

But the day the diet ended, Donald Trump was elected president, and “I reintroduced tequila immediately. Then I ate candy for breakfast,” Kutner said. “And I just kept eating like shit for two years, because we live in hell.” So this January, she decided to redo the Whole30 diet as a way to improve her overall health.

If you spend an unhealthy amount of time tapping through former co-workers’ and high school crushes’ Instagram stories, you’ve probably noticed that an awful lot of people are doing Whole30 this month. The Whole30 diet has been criticized for being too restrictive (as it turns out, a lot of foods that taste good have sugar in them!), and it has not yet been subject to peer-reviewed research. Nonetheless, it’s won over dieters on Instagram, who have posted 3.9 million #Whole30 photos of vibrantly hued cauliflower steaks and pesto chicken-stuffed sweet potatoes.

Whole30 is incredibly popular as a New Year’s challenge, with searches spiking every January over the past five years, according to Google Trends. Ashleigh Morley, a branded content director who had her first baby last year, decided to try it this January with her husband, partially as a way to shed the weight she’d gained during pregnancy. “We were honestly just eating like crap over the holidays, so in early December we both agreed to try Whole30 as a way to eat cleaner in the new year,” Morley said. “The overall goal is just to make more mindful, healthy decisions after this.” She’s been documenting it on social media to help keep her accountable, and so far, she says, it’s been working.

But Whole30 is far from the only 30-day New Year’s challenge out there, and not every New Year challenge focuses on diets. Even a brief perusal of social media during the month of January will yield hashtags for 30-day fitness challenges, vocabulary building challenges, sobriety challenges, journal-keeping challenges, and even sex challenges.

For those who are constantly focused on becoming better versions of themselves, there’s no shortage of programs to help you do that, albeit in the short term. But the goal of most 30-day challenges isn’t just to shed pounds or hit the gym a few times or learn a handful of cool new SAT words to drop into conversation: It’s to build lasting habits that persist beyond the new year. The question is: Does that actually work?

What are 30-day challenges, and where do they come from?

In and of themselves, there’s nothing particularly revolutionary or unique about 30-day New Year challenges: They’re basically just lengthier, more hashtag-optimized versions of New Year’s resolutions. But the concept appears to have been popularized by “Try something new for 30 days,” a viral 2011 TED talk by then-Google software engineer Matt Cutts (which was itself inspired by the stunt documentary filmmaker Morgan Spurlock).

According to Cutts, the idea for the challenges took root while he was watching TV in May 2009. “It was the end of the season, and I thought, ‘What if I didn’t watch TV for a month? What would that be like?’” he told me. He decided to abstain from watching TV for 30 days, because he thought “a month was a convenient marker.”

By the end of the 30 days, he was stunned by how easy it had been and how much his overall happiness level had improved sans TV. So he decided to take on more tasks, including biking to work every day, taking 10,000 steps every day, or writing a novel. As Cutts explained in the TED talk, the goal was not to totally overhaul his life, but to adopt “small, sustainable changes,” which he found “were more likely to stick.”

Cutts’s TED talk wasn’t limited to New Year challenges, but 30-day challenges are particularly popular during the month of January, says Whole30 creator Melissa Hartwig Urban. “‘New year, new you’ messaging is everywhere. Basically, everyone in the diet and fitness industry sees an uptick in January,” she told me.

Many people will try them as a way to compensate for the havoc they’ve wrought on their bodies during the party-apps-and-cocktails-filled holiday season. “Temptation is around every corner, [and people are] running around shopping and gift-wrapping and entertaining kids during school vacations, and stressed about money and spending time with family,” she says. “So people think, ‘It’s unfair to make myself stay on track now, with everything going on. I’ll just treat myself, and the resolutions I make come January 1 will get me back on track.’”

There is, however, one major problem with this school of thought: New Year’s resolutions notoriously do not work. Research shows that resolutions are largely ineffective when it comes to establishing long-term behavior. According to one University of Scranton study, only 8 percent of people actually achieve their New Year’s resolutions in the long term, and the vast majority (almost 80 percent) will fail before the second week of January.

So why 30 days, exactly?

The idea behind 30-day challenges appears to be that unlike resolutions, 30-day challenges provide a set amount of time for you to follow through on your goals, whether that’s losing weight or refining your diet or trying to avoid using “like” or “um” in casual conversation. The idea is that doing something consistently for 30 days will help you establish a healthier attitude toward indulgences (food, alcohol, Paris Hilton memes on Instagram, etc.) in the long run.

“It’s not only a measurable amount of time (a clear beginning and end, something to look forward to), but it’s also adequate time to really make a change,” says Keri Glassman, a registered dietitian nutritionist and the CEO and founder of the lifestyle and wellness company Nutritious Life. “It’s long enough that your system will have adapted at least partially to your diet or exercise routine, making it more likely to stick to (again, at least partially!). After going to the gym every day for 30 days, it’s less likely you’re going to never go again.”

It also has benefits for the wellness dilettantes among us who may want to dabble in keto or Paleo or vegan without going whole hog: 30-day challenges “allow people to feel like they’re trying something new without the commitment of saying that they want to incorporate those habits into the rest of their lives,” says Glassman.

This seems to be the basic reasoning behind Drynuary, a month-long period of sobriety that’s probably the most popular 30-day challenge on social media. Although the concept of abstaining from alcohol during January has been around for years, the term itself was purportedly coined by journalist John Ore, who practices Drynuary every year as a way to save money, detox from New Year’s excesses, and “consider the role alcohol plays in our everyday lives,” he wrote in a Slate piece. The goal is not so much to abstain from alcohol in the long run, but to build a healthier relationship with booze that informs your everyday life.

It’s unclear where the precise “30-day” figure actually comes from (other than the fact that it’s the average length of a month), but another number that’s frequently tossed around in behavioral psychology circles is 21 days, or three weeks, which stemmed from plastic surgeon Dr. Maxwell Maltz’s observations of how long it took for his patients to become accustomed to their new faces. Although the 21-day myth has been debunked multiple times by behavioral researchers, wellness gurus like Dr. Oz have continued to regurgitate it, which has led to many accepting it as fact.

Thirty-day challenges also may be based on recent studies on habit formation, such as this 2015 paper by Navin Kaushal and Ryan Rhodes in the Journal of Behavioral Medicine, which looked at a group of participants who were asked to hit the gym over the course of 12 weeks. The study authors were interested in finding out how often participants had to go to the gym in order for it to become a habit. They found that “rises in habit appeared to peak at around six weeks, particularly for those who were exercising at least four times per week, and stabilized after that time,” Rhodes told me.

Rhodes cautions that the 2015 paper is by no means the end-all, be-all authority on habit formation: The study results have yet to be replicated with other samples, and there was a lot of variability among his study’s participants. “Until we have more estimates for habit formation, we should be cautious about this finding. It’s interesting, but not the final say on the topic,” he says. Nonetheless, 30-day challenges have exploded — even though, in light of the research surrounding 21 days and 42 days, the trend may simply be the result of splitting the difference between the two figures.

So do 30-day challenges actually work?

That depends on what the challenge is, and what you’re actually trying to achieve.

Generally speaking, short-term weight loss and dietary challenges “can be effective to help teach better, sustainable eating habits,” says Cassandra Forsythe, a nutrition scientist based in Manchester, Connecticut. “But if they are too restrictive, they can also backfire.” Glassman also cautions against people doing shake or juice cleanses, which can be wildly unhealthy, not to mention ineffective. “After a diet like that is over, you have taken on no new healthy habits or lifestyle changes, which is why the weight comes back after you’re done sipping on less-than-tempting chalky shakes,” she says.

Glassman says short-term diets like Whole30 can help “teach you how to incorporate healthy habits into your life,” such as swapping out fruit for sugary snacks. Forsythe, however, cautions that anyone trying Whole30 to lose weight is fighting an uphill battle: “It is very restrictive, and it isn’t something many people can maintain for long.”

To be fair, Whole30 doesn’t actively market itself as a weight loss plan so much as an experiment to help guide you to develop healthier eating habits: “We’re not a diet at all, in that you’re not counting or restricting calories,” Hartwig Urban says. “We’re a 30-day self-experiment that helps people figure out what works for them while addressing people’s habits and emotional relationships with food.” But most coverage of Whole30 does point to weight loss as a benefit, and there are no independent studies to back up these claims. Further, short-term diets do little to help keep weight off in the long run, and can even serve to slow down your metabolism.

“I’ve run weight loss studies, and most are done for a minimum of 12 weeks to see any change in bodyweight. But most are longer,” Forsythe says. “Then to keep weight off, the weight has to have come off with sustainable methods [that] can be maintained,” such as exercise and eating processed, sugary foods in moderation.

The key to achieving your goals in a 30-day challenge is keeping your goals small and achievable, says Rhodes: Aim for goals “that are achievable in our busy schedules (i.e., keep it simple) and ways to tie our behaviors to our existing routines.”

Giacomo Barbieri from New York City Personal Training and Limelight Fitness regularly works with clients on 30-day fitness challenges, and says that focusing on small goals will make them that much more achievable: Instead of promising to hit the gym more, or abstaining from alcohol entirely, “walk the stairs instead of using the elevator, or when you’re at a party, drink two glasses of wine instead of four,” he says. “All these daily actions will reflect [heightened] awareness of your health.”

While this may sound obvious, it’s also a good idea to do something that you actually enjoy doing, in lieu of something you hate. “If you didn’t like going to the gym last year, chances are you will feel the same this year,” Rhodes advises. “Choose a different activity.” You should also try making small tweaks to your routine to make dreary and repetitive activities more enjoyable. “When I started biking to work, I thought, ‘I hate biking to work. This is hard, you get sweaty, it’s not much fun,’” said Cutts. “Within 30 days I thought, ‘You can find ways to make it easy and enjoyable,’” such as finding shortcuts or getting new gear (he’s partial to light-up helmets and side-saddle bags). Now, he says he bikes to work all the time.

Like anything else in life, your ability to execute on a 30-day challenge, whether you’re trying to eat better or learn how to use the word “lugubrious” in the appropriate context, is dependent on multiple factors, such as your level of commitment and whether you have a support system in place (some studies, for instance, have shown that couples who try to lose weight together are more likely to be successful than those who go at it solo).

It’s also important to note that access plays a role here: Those who can afford personal trainers and expensive meal delivery kits are more likely to achieve their health and fitness goals than those who can’t. (When asked if current behavioral research on habit formation controls for factors such as income, Rhodes says that it “has not been applied to enough different populations yet to understand how well it generalizes.”)

That said, if you’re midway through a grueling Drynuary, or if you’re doing Whole30 and scrolling through photos of egg-and-avocado food porn on Instagram is losing its motivational luster, take this lesson to heart: Even if you fail a 30-day challenge, you will ultimately get something out of it. “I think raising awareness about rethinking health behaviors is a wonderful idea,” says Rhodes. “Any time we can take stock of our life and try to change our behavior can be helpful. What we need to do from there, however, is be realistic about the changes we make and do the best that suits our lifestyle and current situation.”

And who knows? You might get something out of it that you didn’t expect. By doing the Whole30 diet, “I’m learning that pork gives me gas,” Kutner said. “So that’s something.”

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