Carbohydrates sit in your stomach for the least amount of time, as compared to the other macronutrients -- protein and fat. You may think it’s a bad thing that carbs scurry through your digestive tract, but they’re a major fuel source for all cells so they have to be on their way.
Sugars vs. Starches
Sugars digest faster than any other nutrient in your diet. They head straight down to your small intestine, quickly convert into glucose -- your body’s main type of fuel -- and go right into your bloodstream through intestinal walls. Starches need a little work done before entering your blood. When you eat something with starch, the saliva in your mouth starts deconstructing it right away. Saliva splits apart long, branched starch compounds, turning them into maltose, a type of sugar molecule. By the time maltose hits your gut, it still has to wait for enzymes to arrive to convert it into glucose. But once the conversion process is over, the resulting glucose particles are free to go to your bloodstream to power cells.
Effects of Carbs
Once glucose from carbs reaches your bloodstream, you’ll feel energized. Sugar leaves your belly quickly. So if you eat something that is high in sugar, you’ll most likely get that sugar-high feeling and then crash shortly after. But if you have something high in starch -- think potatoes or whole grains -- the slower digestion rate gives you more sustained energy over a longer period of time.
The Fiber Consideration
Fiber is a carb, although it doesn’t turn into glucose and doesn’t add any calories to your diet. Instead, fiber travels through your digestive tract intact for the most part, and helps nutrients absorb while pushing out waste. Fiber can make food sit in your stomach a little longer, including carbohydrates from the food you eat. So if you ate an apple, for example, which is high in both fiber and fructose, a fruit sugar, the sugar may not give you instant energy since fiber holds it back for a bit. But, if you were to drink apple juice, you’d miss out on the fiber and get straight sugar for quick energy.
How Much You Need
Since carbohydrates are your body’s main energy source, the biggest chunk of your calories needs to come from them. Forty-five to 65 percent of the calories in your diet need to come from carbs, according to the Dietary Guidelines for Americans 2010. You get 4 calories from each gram of carbohydrate. If an 1,800-calorie daily diet is typical for you, meeting the recommendation means that you should aim for 202 to 292 grams of carbohydrates each day. But fiber is separate. Because fiber doesn’t have calories, it has its own recommendation of 14 grams per every 1,000 calories you consume. Based on 1,800 calories daily, you’ll need 25 grams of fiber every day.
Melodie Anne Coffman specializes in overall wellness, with particular interests in women's health and personal defense. She holds a master's degree in food science and human nutrition and is a certified instructor through the NRA. Coffman is pursuing her personal trainer certification in 2015.