Read labels to calculate the net carbs in food.
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When you eat a carbohydrate-restricted diet, it's important to know that not all carbohydrates affect your blood sugar and metabolism in the same way. The net carbs in a product equal the number of carbohydrates left when hard-to-digest substances such as fiber and sugar alcohols are subtracted from the total carbohydrates.
It's simple to calculate net carbs from a food label. Look at the total amount of carbohydrates, and then subtract the number of grams of fiber and half the grams of sugar alcohols.
Calculating Carbs from Dietary Fiber
Dietary fiber is a type of carbohydrate that isn't digested by your body. As a result, it doesn't affect your blood sugar levels. So a food label that shows 10 grams of carbohydrates per serving with 5 grams of dietary fiber would only contain five net carbs. However, many foods that you'll find in the grocery store contain a minimal amount of fiber. A typical granola bar might have 44 grams of carbohydrates with less than 3 grams of dietary fiber, for a net carb content of 41 grams. Instead, opt for low-carb, high fiber options such as hemp hearts. They have just 3 grams of carbs in a 1-ounce serving, and nearly 100 percent of that is fiber.
Calculating Net Carbs From Sugar Alcohols
Despite their name, sugar alcohols contain no alcohol, making them safe for non-drinkers to consume. Instead, these sweet carbohydrates get processed from other sugars or occur naturally in foods. They have fewer calories than sugar and have minimal effect on blood sugar, because the body absorbs roughly half as much. For example, a sugar-free candy bar with 29 total grams of carbs and 18 grams of sugar alcohols would have 20 net carbs after subtracting half (9 grams) of the sugar alcohols.
Don't go overboard with sugar alcohols. Because they aren't completely absorbed, they can cause gas or other unpleasant gastrointestinal side effects due to fermenting in the colon. Erythritol found in stevia and the sweetener blend Truvia is an exception. About 90 percent gets absorbed by the small intestine but is excreted in the urine, with the other 10 percent passing through the colon without fermenting.
Calculating Carbs From Sugars
Carbs in the form of sugars and starches convert to glucose, providing energy to the brain and central nervous system. However, any excess gets stored as fat in the body. When you see "sugars" listed under the carbohydrates on a nutrition panel, you know that the entire amount of the sugars will be absorbed and converted to glucose in your system, so do not subtract the amount from the total carbs.