We know we’re supposed to stock our fridge with healthy, whole foods; meal-prep on Sundays; and never, ever fall victim to the vending machine. But real talk? Sometimes, all we have the energy for is opening up a packaged meal or snack.

And that’s OK, if you do a little reading first. By now you probably know it’s smart to check out the nutrition facts when you pick up a packaged food. But it’s not necessarily the first thing you should be looking at.

Wait, what? Yep, before you search for the protein, fiber, sugar, fat, and calories, zero in on the ingredients list. Think of it as the eyes that help you see what’s in the package before you even open it. Here are four important things you’ll learn from that (ideally short) list—and why it’s smart to read it in addition to the nutrition facts.

1. You’ll see what your food is *really* made of

A pretty picture (fruit) or a wholesome description (made with whole grains!) on the front of the package might suggest one thing, but the ingredients list is where you’ll get the real story.

Not only will it tell you what a food is made of, but it can also give you clues as to how much of a certain ingredient is in a food. “Ingredients are listed by weight, with the first three to five ingredients typically making up 80 percent of the product,” says Ali Miller, R.D., author of Naturally Nourished: Food-As-Medicine for Optimal Health.

If you spot clean, minimally processed ingredients—whole foods such as fruit or nuts—near the top, you can feel good knowing those ingredients make up the bulk of the food. But the opposite is also true. If the first few ingredients on the list are things such as sugar or refined flour, then you’re eating mostly, well, sugar and refined flour. In fact, the ingredients list is a much better indicator of how much added sugar is in whatever you’re eating, since the grams listed under nutrition facts include all sugar, including the kind that naturally occurs in fruit, vegetables, and dairy.

From Our Partner: RXBARs have always contained 100 percent whole-food ingredients. The brand knows you care about what you’re putting in your body, so it puts the main ingredients (egg whites, dates, nuts) front and center on the wrapper. Read the back, and you’ll see each protein bar is also filled with delicious, real foods such as fruit, cacao, and coconut.

2. You’ll think outside the calorie box (for once!)

The nutrition label is a quick way to help you rate a food on a pass/fail basis. If it meets your needs for things such as calories, protein, fiber, or fat grams, it passes. But it doesn’t tell you whether your food is actually an A+, a C, or a D-.

Just because a food has a certain number of calories or macronutrient grams doesn’t automatically mean it’ll give you the most nutritional bang for your buck, explains registered dietitian Jess Cording. “A slice of white bread and a slice of sprouted grain both deliver around 100 calories,” she says. “But the white bread is made with refined grains that will cause your blood sugar to quickly spike and crash, while the sprouted brain is made with whole grains that offer nutrients such as fiber and B vitamins,” she says.

From Our Partner: RXBARs are the perfect on-the-go snack because they’re packed with 12 grams of protein (from egg whites, no less) but contain no added sugar (dates provide all the natural sweetness you need). Translation: They keep you full and satisfied for hours, with no sugar crash.

Try the whole-food protein bars for yourself. RXBAR is giving Greatist readers 25 percent off a 12-bar sample back that includes some of its best flavors—chocolate sea salt, peanut butter, and mixed berry, for starters—plus free shipping.

3. You’ll identify the ingredients you want to avoid ASAP

If there’s something specific you’re looking to steer clear of, scanning the ingredients list is the best—and sometimes the only—way to do it. Sure, there are label certifications that can tell you whether a food is gluten-free or made without GMOs. And while those are important, you can’t rely on verifications for every single ingredient. After all, there’s no third-party certification guaranteeing a food is free of strawberries or cilantro.

Checking the ingredients can help you avoid the ones you dislike or have an intolerance to. But it’s also important for avoiding ones that are straight-up dangerous, like trans fats. For now, foods can contain up to 0.5 grams trans fats per serving and still list 0 grams per serving on the nutrition panel. (Starting in 2018, manufacturers will no longer be allowed to add trans fats to packaged foods.) For now, the only way to tell for sure whether your food is truly trans fat-free is to check the ingredients list for hydrogenated or partially hydrogenated oils, Cording says.

From Our Partner: RXBAR keeps things simple. Its protein bars are naturally gluten-free, dairy-free, and soy-free, because they’re pretty much just egg whites, dates, and nuts. The extras RXBAR does add are there for a reason: Cocoa and cacao add a punch of chocolaty flavor without added sugar or dairy, real fruit provides flavor and texture, and spices such as ginger and cinnamon bring out the unique taste of each bar.

4. You’ll know if the food is minimally processed

News flash: The term natural isn’t regulated. So if you’re looking for a packaged food made with ingredients that legit come from nature, the ingredients list is where you go. Spot a bunch of unrecognizable, hard-to-pronounce ingredients? That can be a sign the food in question is highly processed (we’re looking at you, monosodium glutamate and butylated hydroxyanisole). See a list of real foods you could actually buy yourself? Now you’ve got something with ingredients that are much closer to their natural state, Miller says.

Of course, this isn’t a hard-and-fast rule. Some ingredients that sound chemical-y—such as ascorbic acid (which is really just a fancy name for vitamin C)— are perfectly safe, so it’s important to do your research.

From Our Partner: Here’s what you won’t see on an RXBAR label: artificial colors and flavors, preservatives, and fillers. Here’s what you will see: actual foods you recognize and love, such as almonds, cashews, raspberries, blueberries, pecans, and coconut.

The bottom line

Nutrition panels are chock-full of good information, and they can help you track your calories and macronutrients. But they’re only part of the whole picture. Next time you’re thinking about buying a packaged food, make the ingredients list your first stop. Once you’re sure it meets your standards, you can start thinking about the numbers.