What’s the Difference Between Good and Bad Carbs?

Reviewed by Poonam Sachdev on June 22, 2021

Carbohydrates have a bad reputation. They tend to take the blame when people gain weight – but are they the true culprit?

It’s true, there are some bad carbs, but not all carbs are bad. Many carbs are important because they get turned into fuel for your body. 

Carbohydrates are naturally found in plant-based foods, and these are typically good carbs. This type of carb is also called a complex carb, which promotes a healthy digestive system and metabolism.

Bad carbs are added to processed foods as starches and sugars, which have a variety of consequences. These are called simple carbs, which are absorbed into the bloodstream and become blood sugar

Simple and Complex Carbs

Carbohydrates are broken down into two broad categories: simple and complex. 

Simple carbs are the bad kind. These are carbohydrates that have many of their necessary nutrients removed. Simple carbs are digested quickly, causing spikes in blood sugar and making you feel hungry sooner. The short-lived fullness leads to overeating, weight gain, and conditions like diabetes and high blood pressure. 

Popular foods with simple carbs include:

  • White bread
  • Enriched or refined pasta
  • Enriched or refined dough
  • Pastries
  • White rice 

Complex carbs are the good kind. They are often packed with nutritional layers like bran and fiber that make you digest them slower. Not digesting as fast also leads to a slow but steady release of glucose, preventing spikes in blood sugar.

Opting for a whole grain alternative to some of the above popular foods provides two major benefits. First, you get the same food but as a complex carb and with all the benefits that accompany it. Second, you are less likely to eat something processed that has a lot of added sugars.

Fibers, Starches, and Sugars

Carbohydrates are further broken into three more categories: fibers, starches, and sugars.

Fiber comes from plant-based foods. Fiber is a complex carb that isn’t completely broken down during digestion. Instead, it passes through your intestines and helps digest other nutrients. It also helps you feel full longer, preventing overeating. 

Good sources of fiber include:

  • Legumes such as lentils, beans, and peas
  • Fruits and vegetables with edible skin or seeds
  • Nuts and seeds
  • Whole grains such as quinoa and oats 
  • Brown rice, pasta, and cereals made of whole grains 

Starches are complex carbs. Starches function similarly to fiber. You digest them slower and they provide vitamins and minerals.

Starches are also found in many of the same foods:

  • Legumes, primarily beans and peas
  • Fruits
  • Whole grains
  • Vegetables, primarily corn and potatoes 

Sugars come in two forms: natural and added. Natural and added sugars are simple carbs, which means they are processed by the body quickly. The sudden spike and subsequent quick drop in blood sugar is often known as a sugar crash. 

Your body can’t tell the difference between natural or added sugar. Consider this: eating a candy bar provides your body with sugar and not much else. Eating fruit still provides sugar, but it also supplies your body with important fibers and starches. 

Added sugars might also be called:

  • Dextrose
  • Fructose
  • Lactose
  • Sucrose (table sugar)
  • Beet sugar
  • Honey
  • Corn syrup
  • Turbinado
  • Agave 

Benefits of Healthy Carbs

With all of this in mind, the benefits of healthy carbs become clear. Because carbs are fuel for your body, a lack of healthy carbs can have negative effects.

Carbs fuel several organs and systems, such as your:

  • Brain
  • Kidneys
  • Heart muscles
  • Central nervous system
  • Digestive system 

Fueling these organs strengthens them and prevents conditions such as diabetes and heart disease. Additionally, extra carbs are stored in your muscles and liver, so if you don’t get enough carbs later, your body still has stored up energy to use. 

A diet without enough carbs can lead to:

  • Headaches
  • Fatigue
  • Weakness
  • Lack of focus and difficulty concentrating
  • Nausea
  • Constipation
  • Vitamin and mineral deficiencies 

Choosing Healthy Carbs

You don’t have to be a nutritionist or counting carbs to benefit from a diet of healthy carbohydrates. 

The Plate Method is a powerful way to focus on healthy carbs. Half of your plate should be fiber-rich and starch-free vegetables. A quarter of the plate should be starchy foods, whether that’s vegetables like potatoes or a fruity dessert. The last quarter of the plate should be lean protein. 

It can be difficult quitting bad carbs. Rather than cutting away pieces of your diet, find replacements for them. Instead of soda, try sparkling water. In place of white bread, opt for whole-grain bread. With a little bit of work, you can replace bad carbs with good carbs. 

Show Sources


American Diabetes Association: “Get to Know Carbs.”

American Heart Association: “Carbohydrates.”

Cleveland Clinic: “Carbohydrates.”

Diabetes Food Hub: “What is the Diabetes Plate Method?”

Mayo Clinic: “Carbohydrates: How carbs fit into a healthy diet.”

Reid Health: “Carbohydrates 101: The benefits of carbohydrates.”

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