Can protein bars do you more harm than good?

In honour of the 'Mean Girls' 10-year anniversary, we've been obsessively watching (and re-watching) our favourite 'Plastics' clips -- for research purposes, of course.

By far one of the hallmarks of the classic high school flick is when Cady tricks Regina into eating a nutritional bar, claiming it will "burn up all her carbs," only to cause her to pack on pounds.

And while the film may be a decade old, the whole thing got us thinking – are those protein bars we scarf down religiously in the name of nutrition actually any good for us?

Also see: On Wednesdays we wear pink: How to wear pink without looking like a Plastic

"I think protein is important, but it can be overstated," Jennifer Sygo, a registered dietitian and sports nutritionist based out of Toronto, Ont., tells Yahoo Canada Shine.

"We think, 'I'm going to the gym therefore I need large amounts of protein and I need protein bars.' Well, in most cases, probably not."

Sygo says that for the average three-day-a-week exerciser, there isn't really any necessary increase in protein requirement. And even for those who exercise daily, the requirement only goes up by another one gram per kilogram of body weight.

Also see: My nail beds suck -- and other beauty problems that aren't just for Plastics

But even if your protein need is higher than average, Sygo warns against relying on protein bars to reach your target amount.

"Even in elite athlete circles, things like protein bars would be considered the secondary option," she says. "The first option is real food, so choosing foods like beans, legumes, meats and dairy, such as Greek yogurt, milk and soy milk."

These whole foods offer a breadth of nutritional benefits rather than offering a single quick protein fix, she says.

Also see: Creative ways to cut calories

"There's also that element of when [a bar] is formulated in a lab not only could there be additives that we know about that aren't healthy, such as added sugars, but there could also be things that we don't know about that are bad for us."

She says often these bars include ingredients that undo the work you put in at the gym. Some common ingredients found in protein and other nutritional bars that we should be wary of include high-fructose corn syrup, which may contribute to belly fat, as well as natural sugars which are marketed as being healthy, such as agave nectar, coconut sugar and evaporated cane juice.

"Sugars can be a very muddy issue because companies are using a lot of natural sugars, which is giving them what we call a 'health halo effect,' which is this image that it's a very nutritious food, when really it's still just sugar," she says.

Also see: Why the 'Whole30' diet is taking over Instagram

"There's a lot of tricky marketing going on that makes sugar look cleaner than it really is, so I'd watch for those sneaky sugars."

Other common sneaky ingredients are sugar alcohols, such as xylitol and sorbitol, as well as inulin; the former add sweetness without raising blood sugar, while the latter is a derivative of chicory root that is used to increase a bar's fibre content. While these ingredients aren't unsafe, they are known to cause digestive issues, such as bloating and tummy aches.

"[They] make the bar look attractive to the consumer on paper… but a lot of people find it makes them feel bloated and gross when they're exercising."

Also see: Are chia seeds really all that great?

Instead of reaching for bars pre- or post-workout, Sygo recommends eating carbohydrates, such as oatmeal or a fruit smoothie, before working out, and having real-food protein, such as nuts and nut butter or meat to help your body recover.

"Toast with peanut butter or pita with hummus is always a good option," she says.

"Talking about old-fashioned food isn't always the sexiest thing, but it works."

Can't get enough 'Mean Girls'? Watch the video below for 10 style tips we learned from the film!