Love ’em or hate ’em, protein bars seem here to stay. The market was valued at $837 million in 2016, and sales are still going up about 4 percent every year. But what about the actual protein bar nutrition facts: Are these bars even healthy? And are they the right choice for athletes who look to protein to help optimize their strength and physical fitness?

The answers, as with most things nutrition-related, are “it depends.” We asked LA-based nutritionist and healthy cooking expert Patricia Bannan, MS, RDN, author of Eat Right When Time is Tight, to help explain the importance of protein, shed some light on protein bar nutrition, and offer some guidelines for choosing your bars wisely.

Why Is Protein So Important, Anyway?

“Proteins are the building blocks for a number of bodily functions, such as the growth and repair of muscle tissue, enzyme and hormone production, as well as hair and nail growth,” Bannan explains. Like carbohydrates and fat, protein is a macronutrient—“that means our bodies require larger amounts of it in the diet than micronutrients such as vitamins and minerals,” she adds.

How Much Protein Do You Really Need?

It can differ based on your age, gender, activity level, and any medical conditions you might have. The standard recommendation for protein intake is 0.8 grams per kilogram of body weight (or 0.35 grams per pound), says Bannan, which is roughly 46 grams per day for adult women and 56 grams per day for adult men.

Athletes might need a little more to help build muscle, but likely not as much as you might think. The Academy of Nutrition and Dietetics recommends 1.2 to 2.0 grams of protein per kilogram of body weight per day for athletes. But, again, it depends on the type and duration of activity you’re doing. “Athletes who are powerlifting or exerting a lot of muscle strength for a longer period of time may need more protein than an endurance athlete,” says Bannan.

The best time to get that extra protein might be post-workout: Research suggests that consuming protein after exercise is important for muscle repair and growth. But that doesn’t mean you have to scarf down a protein bar the moment your workout is over, says Bannan. “Eating a high-quality protein source within a two-hour window after a workout or intense exercise is effective.”

That said, protein isn’t the only thing you should reach for—carbohydrates are important, too. “It’s best to consume both carbohydrates and protein in the two-hour window post-workout to assist with both protein and glycogen synthesis,” explains Bannan. She recommends snacking on something that has a 3:1 ratio of carbohydrates to protein.

What to Look For On a Protein Bar Nutrition Label

When you’re looking at protein, consider both the intensity and duration of your workout, and how much protein you’ve already consumed that day.

“A lot of times, people are actually taking in more than enough protein than they need in a day,” says Bannan. “And loading up on protein doesn't necessarily equal more muscle tone or strength.” In other words, enough is enough, and more than enough probably won’t serve you any better.

As for calories, consider whether you’re eating the bar as a snack or a meal. “If you plan to eat a balanced meal within the next few hours, opting for a bar in the 200-300 calorie range can be enough,” says Bannan. “If the bar is replacing a full meal, opt for a higher-calorie bar, or pair it with another food option such as fruit with nut butter or a Greek yogurt, which can be more satisfying.”

One more thing to consider when it comes to protein bar nutrition: Many bars can contain higher amounts of sugars or sugar alcohols like maltitol and erythritol, which could result in stomach upset, warns Bannan.

Her rule-of thumb advice for athletes: “If you don't have time to prepare a full meal or snack after a workout, a protein bar can be a convenient option. Just remember they’re not a necessary component for muscle growth or repair.”