Ever feel like totally starting over when it comes to your eating habits?

The Whole30 diet thinks it can help. The program’s been around for nearly a decade and boasts tons of success stories—but other than the fact that it’s 30 days long, the specifics of the program might seem a little murky to someone just starting to do their research.

Here’s what you need to know about Whole30, the popular diet program designed to change the way you eat—and feel—in just 30 days.

What exactly is Whole30?

The Whole30 diet is essentially an elimination diet, according to the program’s website. It recommends stripping certain food groups from your diet—like sugar, grains, and dairy—to see if they might have a negative impact on your health.

The idea, per Whole30’s website, is that by eliminating “blood-sugar disrupting, gut-damaging, inflammatory food groups” for 30 days you can let your body heal and recover from whatever effects those food groups may have on you (low energy levels or chronic pain, for example). Once the 30 days are up, dieters are encouraged to use a long-term “Whole30-ish” meal plan to slowly and sparingly introducing some foods back on, based on how they make you feel.

Also important: According to Whole30 co-founder Melissa Hartwig-Urban, Whole30 wasn’t designed as a weight-loss plan—in fact, Hartwig-Urban calls it the “anti-diet” since there’s no counting, tracking, or restricting calories. The diet also urges you not to step on the scale for the 30 days. Still, there’s no denying that a ton of people do lose weight while they’re doing the Whole30.

So…where did Whole30 come from?

Whole30 basically started in April 2009 when Whole30 co-founder, Melissa Hartwig-Urban carried out her own experiment of eliminating anti-inflammatory foods from her diet for 30 days to see if it would help her perform better in the gym.

And according to Hartwig-Urban, it worked: “I slept better, had more energy, focused better at work, and was happier in general,” she says. “But what the experiment really helped me change was my emotional relationship with food. For the first time in my life, I got off the scale and out of the mirror, and found other ways, besides junk food or wine to self-soothe, reward myself, and show myself love.”

Hartwig-Urban shared her experience on her blog, and, well, the rest is history.

Okay, what foods can’t I eat on Whole30?

Brace yourself, because there are quite a few.

On Whole30, you’re instructed to give up added sugars—real or fake, per the website. That means maple syrup, honey, and even stevia are off limits. You’re also supposed to read the labels of anything you buy since added sugar can sneak in anywhere.

Here’s the hard part: You’re also asked to give up all grains (wheat, oats, quinoa, etc), legumes (beans, peas, lentils), and dairy (all cow- goat- and sheep’s milk products). That includes any meat alternatives like tofu and tempeh (they’re technically legumes, made from soy).

You’ll also need to sidestep common additives in processed foods like carrageenan, MSG, and sulfites (you’ll have to check the labels again for those).

And don’t think you can cheat the system, either: According to the website, you’re also not allowed to eat any treats, even made with “approved” ingredients. So even if your pancake is made from Whole30-compliant coconut flour, it’s still off-limits.

Oh, and don’t even think about drinking any booze.

Well, what can I eat on Whole30?

According to the Whole30 website, the first rule of the program is to “eat real food.” That means meat, seafood, eggs, vegetables, fruits, natural healthy fats (like olive oil and nuts), and herbs, spices, and seasonings. You’re also allowed coffee and tea on the diet (just make sure you take it black).

Basically, you’re going to want to shop the farmer’s market or stick to the outer perimeter of your supermarket. And while you don’t have to buy grass-fed meat or organic produce, Hartwig-Urban says reading labels (and making sure you can pronounce your ingredients) is key, and will hopefully turn into healthy, long-term habits.

Should I give Whole30 a try? And if so, how do I start?

Overall, feedback on the Whole30 is mixed. The U.S. News & World Report’s most recent ranking of diets put the program at #37 out of 40, with an expert panel of registered dietitians, academics, and medical doctors throwing shade at it for being unsustainable and potentially unhealthy.

That said, millions of people have followed the program and loved the results, according to Whole30’s website.

If you think you can live without carbs for 30 days, the Whole30 might work for you. But you may want to steer clear if you have a history of disordered eating—making entire food groups “off-limits” could lead to disordered eating patterns, warns Turoff. She also notes that the plan may be tough for vegans and vegetarians because dietary staples like legumes and grains aren’t permitted.

Otherwise, the Whole30 could be a healthy choice for many people, as it provides all the nutrients your body needs. It may not be sustainable as a long-term plan, but it’s a no-brainer that 30 days of eating unprocessed, fresh, high-quality foods comes with some benefits.

If you want to get started, go ahead and download theWhole30 Program PDF. For an even deeper dive into the diet, you can also snag The Whole30and its companion The Whole30 Day by Daywhich are both available on Amazon.