# Here's what you need to know about counting net carbs to lose weight

The easiest way to calculate your net carbs is to subtract fiber from your total carbs.

For example, plans like the Atkins 20 require you to aim for an average of 20 grams of net carbs per day in your first two weeks of the diet to kickstart weight loss. But what exactly are net carbs—and are they different from regular carbs?

In short, yes. Net carbs are the amount of carbohydrates left over in a product after you’ve subtracted the fiber and sugar alcohol from the total carb count. “The theory is that since your body doesn't digest most of the fiber, and sugar alcohols are also largely indigestible, they don’t need to be counted,” says Alexandra Caspero, R.D., owner of Delish Knowledge.

But does counting net carbs really work? Here's what you need to know.

HOW TO CALCULATE NET CARBS

The easiest way to calculate your net carbs is to subtract fiber from your total carbs. Some people will subtract fiber and sugar alcohol, but sugar alcohols are not listed on most foods, making them difficult to calculate. "Net-carb calculations aren't a set standard," says Caspero. "Some people will 'calculate' them differently; either just subtracting fiber or subtracting both sugar alcohol and fiber."

The basic formula looks like this:

Net Carbs = Grams Total Carbohydrates – (Grams Fiber + Grams Sugar Alcohol)

For instance, maybe you have a slice of bread that has 15 grams of total carbs and five grams of fiber and two grams of sugar alcohol. Your net carbs for this slice of bread then would be eight grams.

If you were on phase one of the Atkins 20 diet, that means you'd still have an allowance of 12 grams of net carbs for the rest of the day. In later phases of Atkins 20, you'll increase your net carb intake to as much as 80 to 100 grams per day.

SHOULD YOU BE COUNTING NET CARBS?

Calculating net carbs for weight loss is based in the idea that some carbs, like fiber and sugar alcohol, don’t affect your blood sugar levels and therefore won't affect your weight. Because of this, they don’t need to be counted in your total carb intake.

But is there really such a thing as carbs that don’t "count"?

Here's the deal: When carbs are broken down in your body they become sugar—a.k.a. glucose. If you have high amounts of glucose in your blood, then you are at risk of weight gain. "If blood glucose remains elevated then the body may begin to store energy as fat," says Cara Harbstreet, R.D. of Street Smart Nutrition.

Net-carb diets encourage you to eat a lot of fiber, with the goal being the fiber won't break down into glucose, add to your sugar levels, and lead to weight gain.

While eating foods high in fiber gets the thumbs up from nutritionists, sugar alcohols don't get the same praise. “Sugar alcohols can still have an effect on blood sugar levels, and too many of them can have a laxative effect,” Caspero says.

Karen Ansel, R.D.N., author of Healing Superfoods for Anti-Aging: Stay Younger, Live Longer, adds that foods low in net carbs can have some uncomfortable side effects on your stomach: "Many foods that are advertised as being low in net carbs have other downsides, particularly stomach upset due to unnatural amounts of added fiber or the use of sugar alcohols."

Following a net carb diet, though, can be beneficial for people suffering from diabetes. "For someone who aims to have better control over their blood glucose levels, being aware of net carbs might be a helpful approach," says Harbstreet. This is because by subtracting those carbs that don't affect your blood sugar levels, you'll know exactly how many carbs you've eaten that will affect those levels.

The bottom line: While counting net carbs might help you lose weight, loading up on foods high in tons of fiber and sugar alcohols may have some unwelcome side effects on your gut. Plus, Harbstreet explains that even though carbs like fiber and sugar alcohol may not affect your blood sugar, "those carbohydrates are still going to be absorbed and used as energy," which means these carbs still add to your total calorie intake.