Can you change your behavior in 30 days?

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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