Maybe you've heard that complex carbohydrates are better for you than simpler ones. But the debate of simple vs. complex carbs isn't as easy as it seems on the surface.

For starters, some foods containing simple carbohydrates, like fruit, are healthy. And certain complex carbohydrates, like white potatoes, have acquired a pretty bad reputation.

When you eat any type of carbohydrate, simple or complex, your body breaks it down into one of the simplest sugar units, glucose, which is absorbed into your blood. The hormone insulin is then released to help move this glucose from the bloodstream into the cells, so it can be used for energy. Insulin also helps store unused glucose in your liver for later use.

What, then, is the difference between simple and complex carbs? And is one really healthier than the other?

What are simple carbohydrates?

Simply put, simple carbohydrates are sugars.

They include the white table sugar we think of when we hear the word "sugar." But they also include naturally occurring sugars such as those found in fruit and milk, and the refined sugars added to many processed foods.

Common examples of foods containing simple carbs include:

• Breakfast cereals
• Yogurts
• Soda
• Candy
• Baked goods
• Fruit juices
  
  

The primary downside of simple carbohydrates is that, because they're so simple, the body breaks them down into glucose very quickly.

"This can lead to a spike in blood glucose," says Amanda Beaver, a wellness dietitian at Houston Methodist. "Insulin release helps that glucose go into our cells, and our blood sugar goes back down. But after this happens we can feel tired and maybe even hungry again."

(Related: Sugar Hangovers: Are They Real?)

One easy way to find out if a food contains a lot of simple carbs is to check the amount of "added sugars" it contains.

"I typically consider foods containing more than 10 grams of added sugars per serving to be high," says Beaver.

What are complex carbohydrates?

Complex carbohydrates include starches and fiber.

Unlike their more simple counterparts, complex carbs contain many sugar units that are attached together via long and/or branched chains. These complicated molecules can be harder for your body to break down.

"Fiber and resistant starches slow down digestion and absorption, so we don't see as fast of a spike in our blood sugar when we eat foods containing these carbohydrates," explains Beaver. "This allows us to feel fuller for longer and also prevents the energy crash we may feel after eating just simple sugars."

The benefits of complex carbs don't stop there. Foods containing fiber and starches also often packed with vitamins, minerals and antioxidants, all nutrients that are beneficial to our body.

Examples of complex carbs include:

• Potatoes and sweet potatoes
• Peas
• Whole grains
• Oats
• Beans
• Hummus
• Lentils
• Fruits
• Corn
  
  

Are simple carbs always bad? Are complex carbs always better?

The two biggest issues with simple carbs are the blood sugar spikes and the potential weight gain they can cause.

A blood sugar spike here and there isn't a huge cause for concern, but over time continued blood sugar spikes can contribute to insulin resistance, which occurs when cells stop responding to insulin. This can further progress into type 2 diabetes, a chronic condition associated with several health complications.

"However, if you want to help blunt the blood sugar spike from a simple carb, you can pair it with a food containing healthy fats, fiber or protein," recommends Beaver. "These all help keep our blood sugar from spiking as fast."

Beaver also notes that simple carbs aren't as filling, which can leave us wanting more.

"This means we tend to eat more of them," says Beaver. "Our brain also responds to simple sugars by releasing serotonin and dopamine. This is why we may feel good when we eat foods containing them and why they can entice us to go back for more."

(Related: Are Your Taste Buds Sabotaging You From Eating Healthier?)

In addition, if the liver is already full of unused blood sugar, excess glucose is stored as body fat instead, leading to weight gain.

Despite the downsides of simple carbohydrates, complex carbs aren't always the healthier choice, especially when it comes to starchy foods.

"Most of the time, starches are better than sugars," says Beaver. "However, potato chips and white bread are considered starches, and these foods aren't necessarily healthy."

Foods containing simple carbohydrates aren't always the less healthy option either. For instance, the naturally-occurring sugars in a piece of fruit are simple, but fruit also contains complex carbohydrates, such as fiber, and other beneficial nutrients — making it a healthy addition to a balanced meal.

"Rather than simple vs. complex, I prefer to talk about carbohydrates in terms of how processed they are, unprocessed vs. minimally processed vs. highly processed," explains Beaver. "This makes it easier to make healthier choices."

Instead of simple vs. complex carbs, focus on processed vs. unprocessed ones

Classifying carbohydrates by the complexity of their sugar chains makes sense for scientific purposes, but Beaver points out that this can be misleading when it comes to nutrition.

"For instance, white bread, white pasta and white rice are considered complex carbohydrates because, structurally, they have branched sugar chains, but these chains are quickly broken down during digestion because the fiber has been stripped away from the grain," explains Beaver. "Similar to simple sugars, this makes these carbohydrates easier for our body to digest and absorb more quickly."

Another example: Apple juice vs. apple sauce vs. whole apples. The processing used to create apple juice strips out the fiber and many of the antioxidants contained in an apple. Applesauce still contains the fiber, but it's been broken down to the point that it's digested and absorbed much quicker. Whole apples, on the other hand, are unprocessed and still contain intact fiber, antioxidants and other nutrients — making them the healthiest option.

"As we can see, there's a continuum to food processing," adds Beaver. "In general, it is recommended to focus more on less processed carbohydrates rather than more processed versions."

The less processed a carbohydrate, the likelier it is to help slow digestion and absorption, preventing blood sugar spikes and keeping us feeling fuller for longer.

"These foods also tend to be rich in vitamins, minerals and antioxidants," Beaver adds.

This is why, even though potatoes are examples of the complex carbs that the body digests fairly quickly, they can still be a healthy component of a balanced meal.

"Potatoes with the skin contain a lot of fiber," says Beaver. "They also have a bunch of potassium, a nutrient that many Americans do not get enough of. Cooked in a healthy way and eaten in moderation, potatoes can be especially helpful in making sure people meet their potassium needs."

Plus, Beaver points out that the starch in potatoes — as well as other starchy carbohydrates, like white pasta and white rice — can be made more resistant to digestion. This may bring added benefits.

Resistant starch: A way to make starchy carbohydrates healthier?

One way to enhance starchy foods: after cooking them, cool them in the refrigerator overnight and then reheat them when you're ready to eat.

"When certain starches are cooked and then cooled, some of the starch rearranges, forming something called resistant starch," explains Beaver. "Resistant starch helps to feed the beneficial bacteria in our GI tract."

While research is ongoing, preliminary studies suggest that certain resistant starches may also benefit blood sugar by preventing spikes.

"We are still learning about the full benefits of resistant starch, but I recommend it in the meantime because we're eating those potatoes, pastas and rice anyway," adds Beaver. "We may as well just cook it, cool it and maybe benefit from the resistant starches created. It certainly doesn't hurt."