Carbohydrates

Key points
- Carbohydrates include sugars, such as sucrose, fructose, and lactose, and large, complex molecules, such as starch.
- In the body, most carbohydrates get broken down into glucose, a sugar that is the body's main source of energy.
- Contrary to popular belief, whether a carbohydrate is a sugar or a starch has no effect on how fast glucose gets into the blood.
- For example, if a cookie made with sugar has 12 grams of carbohydrate and a cookie made with an artificial sweetener has 12 grams of carbohydrate, the effect on the blood glucose will be similar.
Carbohydrates include sugars, such as sucrose, fructose, and lactose, and large, complex molecules, such as starch.
In the body, most carbohydrates get broken down into glucose, a sugar that is the body's main source of energy. Starches are made of many glucose molecules linked together. Sugars have only one or two molecules, of which one may be glucose.
Contrary to popular belief, whether a carbohydrate is a sugar or a starch has no effect on how fast glucose gets into the blood.
Here are some things that do matter:
- how much carbohydrate you eat at a meal
- the way the food is prepared
- the combination of foods eaten at a particular sitting
For example, if a cookie made with sugar has 12 grams of carbohydrate and a cookie made with an artificial sweetener has 12 grams of carbohydrate, the effect on the blood glucose will be similar. Fat slows down the absorption of food.
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Therefore, adding fat to a carbohydrate food during preparation or at the table will slow digestion of the carbohydrate and delay the effect on blood glucose.
The Carbohydrate–Blood Glucose Connection The lion's share of the glucose in your blood after a meal comes from the carbohydrate in your food. As the carbohydrate is broken down into glucose and absorbed, the amount of glucose in your blood goes up.
Different kinds of foods produce different amounts of blood glucose. There are several reasons for this:
- First, some foods contain more carbohydrates per serving than others. One popcorn cake has 8 grams of carbohydrate, 1/2 cup of kernel corn has 11 grams of carbohydrate, and 1/2 cup of creamed corn has 21 grams of carbohydrate. The more carbohydrate you eat at a meal, the higher your blood glucose level goes.
- Second is how fast the glucose is freed from the food. Carbohydrates come in several forms that take various amounts of time to break down. Food that stays in bigger pieces, like kernels of corn, breaks down more slowly than smaller pieces, like the bits in creamed corn. Cooked food digests faster than raw food. Food that contains liquid (the creamed corn) digests more quickly than dry food (the popcorn cake). Food that digests more slowly will release the carbohydrate into the blood more slowly. Your blood levels of glucose may not rise as high.
- Finally, combination foods, those that contain carbohydrates plus other nutrients such as fat, take longer to digest. This is why ice cream or a candy bar doesn't work well to treat low blood glucose. Your glucose levels may not rise until later because of the fat in these foods.
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By measuring blood glucose levels 1 and 2 hours after your meals, you can get a feel for how different foods and patterns of eating affect your blood glucose levels. You most likely will begin to think about your total carbohydrate intake and how it changes your blood glucose levels. If you plan to eat a certain amount of carbohydrates each day or at a particular meal, you may find that if you eat too many sugary foods, you'll only get to eat a few of the more nutritious - and often more filling - starchy foods.
Written and revised by
David Cohen, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.
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