You’ve probably seen advertisers or bloggers blaming carbohydrates for your inability to lose weight. Or you may have a friend or family member in your life who’s cut carbs as part of a trendy new diet plan.

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While some dietitians have advocated cutting carbs to shed a few pounds, others have suggested the exact opposite. When it comes down to it, what does the science actually say? Are carbs good or bad?

Here's what you should know and understand about carbohydrates.

What are carbs?

According to Live Science, carbs are "one of the basic food groups" and important to "a healthy life." They are the fibers, starches and sugars found in grains, milk products, fruits and vegetables.

"Carbohydrates are macronutrients, meaning they are one of the three main ways the body obtains energy, or calories," Paige Smathers, a registered dietitian, said.

There are three types of macronutrients: proteins, fats and carbohydrates. These are essential to keep our bodies functioning properly. Carbohydrates serve as fuel for our central nervous systems and energy to make our muscles function.

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Are there different kinds of carbs?

Scientists and nutritionists classify carbohydrates into two groups: simple and complex. The chemical structure of each group is actually different.

Simple carbs generally are dissolved by the body quicker, and contain just one or two sugars. These can be readily found in things like candy, soda and syrups. As these foods don't have vitamins, minerals or fiber, they are often referred to as "empty calories" and can more easily lead to weight gain.

Unlike simple carbs, complex carbs have at least three sugars. Often referred to as starchy foods, complex carbs can be found in lentils, beans, peas, peanuts, potatoes, cereals and whole-grain breads.

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Smathers said that while simple carbs may provide a spike in energy quicker, complex carbs provide a sustained source of energy.

"It's best to focus on getting primarily complex carbs in your diet, including whole grains and vegetables," she said.

Simple carbs have previously been linked to an increased risk of heart disease and type 2 diabetes, according to some studies.

Do low carb diets work?

Experts actually tend to agree that low-carb diets are not a sustainable weight loss solution.

Part of this is because its difficult to stick with these diets. A 2013 study by researchers at Harvard University found that only 78 percent of dieters on low-carb plans stuck with it for the long term, according to Health. Conversely, 90 percent of people on high-carb diets stuck with it for the long haul.

While you may lose weight by cutting your carb intake, you can also shed pounds just as easily by adjusting the carbs you eat. Simple carbs have little nutritional value, and should be avoided. Complex carbs will actually provide you with more long-term energy, and won't cause weight gain when consumed in moderation.

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Complex carbs actually provide significant benefits

Carbs may actually have a significant impact on our mental well-being. A 2009 study actually found that people on low-carb, high-fat diets actually were more likely to have depression, anxiety and anger than people on a low-fat, high-carb diet.

Additionally, carbs appear to be important for improving memory. Researchers at Tufts University had a group of overweight women cut carbs entirely from their diet for one week back in 2008. They then tested the women's cognitive skills, spatial memory and visual attention. The women performed worse than a group of other women who had simply reduced their carb intake by a healthy amount.

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To cut or not to cut carbs?

If you're struggling to lose weight, complex carbohydrates are not the problem. You should, however, reduce your intake of simple carbs. Not only do these foods have little nutritional value, they are also often consumed as snacks between meals. One of the big reasons people trying to lose weight often struggle, is that they neglect to cut snacking from their diets.

"People frequently forget about the little things during or between meals that add up calorically and can interfere significantly with weight loss," Dr. Melina Jampolis, a board-certified physician nutrition specialist, wrote for CNN.

Healthy, complex carbs can actually be the key to your weight loss. A 2009 study found that individuals who consumed more fiber, something complex carbs are rich with, lost significant amounts of weight. On the other hand, those who cut fiber from their diet actually gained.

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A balanced diet is the key

A recent study conducted by researchers at Stanford University revealed eating more vegetables along with other whole foods is the key to a healthy diet. The research further suggested that losing weight is more about diet quality than calorie quantity.

According to the research, dieting individuals who reduced their consumption of added sugars, highly processed foods and refined grains (simple carbs) while focusing on increasing their vegetables and whole foods, lost significant amounts of weight over the course of a year without limiting the size of portions.

The bottom line? Just like your overall food choices, the science says the quality of the carbs you consume is what matters most.