How Many Calories Are in a Gram of Carbs?

Carbs — short for carbohydrates — may be a little out of fashion right now, but they are actually a very important nutrient that is the body's first choice for fuel. But how many calories are in a carb is worth knowing when you're thinking about how to control your food portions.

According to the Food and Drug Administration (FDA), there are actually four different types of carbs, which are starches, sugars, sugar alcohols and fiber:

• Sugar is the simplest form of carbohydrate that occurs naturally in fruits, vegetables and milk. A lot of sugar is added to food, too.
• Starch is made up of many sugar units bonded together and occurs naturally in vegetables like potatoes, as well as in grains such as wheat, rice and corn.
• Sugar alcohols are found naturally in small amounts in a variety of fruits and vegetables and are also manufactured and added as reduced-calorie sweeteners to foods such as chewing gum, dairy desserts and sweets.
• Dietary fiber, which can be soluble or insoluble, is found in fruits, nuts and seeds, vegetables, whole grains and pulses. Getting enough high-fiber foods helps prevent constipation, makes you feel full and can interfere with the absorption of dietary fat and cholesterol.

Sugar and starches are the most common carbs, and the 4 calories per gram holds good for this type. (In fact, the British Nutrition Foundation points out that the exact calories per gram of carbs is 3.75, but rounding up makes things simpler.)

Fiber and sugar alcohols are actually slightly different when it comes to calories. Fiber has traditionally been thought of as calorie-free, but the FDA has ruled that soluble fiber should be labelled as having 2 calories per gram and sugar alcohols between 0 and 3 calories per gram.

You've got the skinny on how many calories are in a carb, but don't forget proteins and fats also supply calories. The USDA says protein has 4 calories per gram — the same as carbs — but fat has more than twice this amount, at 9 calories per gram, which means it is easier to overeat fat calories than those from carbs and protein. Why is it, then, that people get so worried about carbs being fattening and unhealthy?

Read more: Recommended Caloric Intake for Weight Loss

The reason may be that many people only think of foods like cookies, desserts and donuts when they hear the word "carbs," lumping all carbs into the "bad for you" category.

In fact, the Harvard School of Public Health explains that dietary carbs are the body's primary energy source, providing the glucose that fuels everything from breathing and thinking to walking and running.

Rather than fixating about the exact calories per gram of carbs, or how many calories are in a carb, the Harvard School of Public Health's recommendation is to focus on the quality of carbs. Making calories in carbs count means choosing more of them in the form of unprocessed or minimally processed whole grains, vegetables, fruits and beans. These deliver vitamins, minerals, fiber and a host of important phytonutrients.

Read more: The Best Healthy Carbs You Should be Eating More of

Carbs to cut down on include white bread, pastries, cookies, sodas and other highly processed or sugary foods. These items contain easily digested carbohydrates that may contribute to weight gain, interfere with weight loss and promote diabetes and heart disease.