You might think carbohydrates are your enemy, but you need them -- a lot of them. During digestion, carbs convert to sugars. These sugars, called glucose, are the main type of fuel for cells, so you have plenty of energy. As a result, the biggest percentage of your calories needs to come from carbs.
Starches are complex carbohydrates. If you’ve ever seen a rubber band ball, with all kinds of layers going every which direction, that’s kind of the molecular structure of a starch. They have several branches of sugars, all balled up into one molecule. It’s the job of your digestive tract to break apart these complex structures and pull off each branch of sugar. Beginning in your mouth, saliva gobbles up starches and starts deconstructing them. As you chew, saliva works hard to convert starch into maltose -- a type of sugar. Once maltose molecules reach your small intestine, which is their first stop after your stomach, enzymes deconstruct them even more until they are broken down all the way into glucose.
Sugars are simple carbohydrates, meaning they have just one or two branches or shorter sugar strands. Since they’re small molecules, they transform into glucose rather quickly. They race down right down to your small intestine where enzymes can rapidly turn them into glucose. Sugars digest quicker than starches, protein and fat.
After the conversion of starches and sugars, glucose molecules go straight through intestinal walls, getting swept away into your bloodstream. The hormone insulin opens up the doors of cells, allowing glucose to go inside. Since sugars break down fast, they’ll give you more of a sudden burst of energy -- that sugar rush feeling. On the other hand, because starches have such a long delay before they get a chance to convert to glucose and enter your bloodstream, think of them as tiny energy capsules. They give you more stable energy over time, rather than instant energy that goes away quickly.
Somewhere around 45 to 65 percent of the calories in your diet should come from carbs, according to the Dietary Guidelines for Americans 2010. All carbohydrates -- both starches and sugars -- have 4 calories per gram. So if 1,600 calories a day is your average, you’ll need 720 to 1,040 calories from carbs, or 180 to 260 grams. Ideally your carbohydrates should come from whole grains, low-fat dairy fresh fruits and vegetables.
A Different Type of Carb
Fiber is indeed a type of carbohydrate, but your body can’t break it down. Because it doesn’t digest, it doesn’t convert to glucose. Instead, fiber moves through your digestive tract, helps other nutrients absorb and sweeps out waste. Fiber has a separate recommendation from other carbohydrates -- 14 grams for every 1,000 calories in your diet, the Dietary Guidelines for Americans 2010 states. So this means if you tend to get around 1,600 calories from your daily diet, you’ll need 22.5 grams of fiber every day.
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