Nutrition shouldn’t be confusing, but it often is and carbohydrates are the perfect example. First you have to figure out which types of carbohydrates are the “good carbs,” no matter what the fad diet of the day tells you. Then you have to know how much you need. There are guidelines to follow, but what’s best for you depends on your activity level and caloric intake.
All carbohydrates -- sugars, starches and fiber -- consist of molecules of sugar connected together. Sugars only have one or two molecules and starches have anywhere from three to thousands of sugar molecules. Starches take longer to digest, but both types are broken down into the simple sugar glucose, which is the fuel that energizes every cell in your body. Fiber is not digested, but as it passes through your digestive tract it lowers cholesterol, moderates levels of blood sugar and prevents constipation. Sugar in processed foods is digested quickly and causes an unhealthy spike in blood sugar. Natural sugar in fruits and vegetables has less impact on blood sugar thanks to the fiber.
Women should consume 130 grams of total carbohydrates daily, which includes all the sugar, starch and fiber you eat. Another way to determine how much you need is to make your carbohydrates account for 45 to 65 percent of your daily calories. Information on the nutrition facts label of a food tells you how many grams of carbs you’ll get in a serving, but not the calories. There are 4 calories in each gram of carbohydrate, so you can easily determine the calories from carbohydrate by multiplying the grams of carbs by four. Use an online nutrient database to determine carb contents for foods without labels. The best sources of carbohydrates are whole grains, beans, nuts, seeds, vegetables and fruits.
Fiber has such an essential role in preventing cardiovascular disease that a separate recommendation was established to be sure that you get enough of your total carbohydrates in the form of fiber. Women should include 25 grams of fiber in their daily diet. Fiber exists in two forms, soluble and insoluble. The soluble type lowers cholesterol and balances blood sugar. Insoluble fiber adds bulk to stool, moves food through your system and keeps you regular. All foods that contain fiber have both types, but as a general guideline, oats, nuts, beans and fruits are better sources of soluble fiber, while whole grains and vegetables have more insoluble fiber.
Exercise and Sports Guidelines
You may need more carbohydrates if you participate in sports or any activity that places increased energy demands on your muscles, heart and respiratory system. Some glucose, in the form of glycogen, is stored in your muscles and liver, but once it's depleted your performance may suffer if you don’t refuel with carbohydrates. Guidelines from the University of Arizona recommend eating 2.7 to 3.2 grams of carbohydrates for every pound of body weight if you train for an hour every day. The amount goes up to 3.6 grams per pound if you train for two hours per day and 4.5 grams for three hours per day.
- Institute of Medicine: Dietary Reference Intakes
- National Academies Press: Dietary, Functional and Total Fiber
- Harvard School of Public Health: Fiber -- Start Roughing It!
- University of Arizona Cooperative Extension: Carbohydrate Needs
- Harvard School of Public Health: Carbohydrates -- Good Carbs Guide the Way
- Harvard University Health Services: Fiber Content of Foods in Common Portions
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