Carbohydrates are sugar-based molecules found in fruit, vegetables, whole grains, and dairy products. The make up about 45% to 65% of calories in a healthy diet (the exact percentage is hotly debated); the rest come from fat and protein.
You'll find carbohydrates in the healthiest foods you eat, and in the least healthy. Check the food label to find out exactly how much is in your favorite foods.
How you eat can affect blood sugar
Choosing the right kind of carbohydrates and spacing them out evenly throughout the day can keep blood sugar from rising too high, too fast (90% of the carbohydrate calories you digest end up as glucose, so they have a much bigger impact on blood sugar than fat or protein).
"The goal ... is to take in enough carbohydrates to nourish ourselves, but never so much that it causes high blood sugars," says Linda Sartor, a diabetes nutrition specialist at the Penn Rodebaugh Diabetes Center at the Hospital of the University of Pennsylvania in Philadelphia.
Up until about the mid-1990s experts believed that people with diabetes should never eat foods that contain so-called "simple" sugarsthose found in cakes and candyand instead eat "complex" carbohydrates, or those with longer chains of sugar molecules such as potatoes, fruit, vegetables, and grains.
We now know that all carbohydrates can cause a rise in blood sugar. Pasta and potatoes, for example, may cause a rapid rise in blood sugar, as can pastries (although other beneficial ingredients in food, such as fiber, cause blood sugar to rise more slowly).
Some carbs are better than others
The goal is now to maximize intake of the good stuffvitamins, minerals, and fiberand minimize carbohydrates that boost blood sugar too much, offer few nutritional benefits, or are packed with fat and calories.
A dietitian or diabetes educator will help you develop a meal plan to get a good balance of carbohydrates, protein, and fat, and an appropriate amount of calories. They'll teach you how to manage carbohydrate intake, usually by carbohydrate counting, but sometimes using the exchange diet, the plate method, the modified food guide, or other meal plans.
You'll need to fine-tune your meal plan by testing blood sugar before and after meals. Specific foods that cause blood sugar to rise too high can vary from person to person (for example, you may find you can only have small portions of orange juice or pasta due to a big rise in blood sugar).
Carbohydrates generally have their peak effect on blood sugar about an hour to two hours after they are eaten, and are gone within three hours.