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How does fiber affect my blood sugar?

By Megrette Fletcher, M.Ed., R.D., C.D.E
Veggie Skewers on the GrillBy Megrette Fletcher, M.Ed., R.D., C.D.E.

Next in our series of posts about how eating affects your blood sugar…fiber. Fiber is indigestible complex carbohydrate, meaning that your body can’t break down the chemical links between the glucose molecules. Therefore, fiber helps fill you up and increases satiety but doesn’t raise your blood sugar or provide energy in the form of calories. (For a great overview of carbohydrates, read chapter 12 of Eat What You Love, Love What You Eat for Diabetes.) Fiber also slows down how quickly food leaves the stomach and this helps stabilize blood sugars in two ways.

  • First, the digestible carbohydrates in foods that also contain fiber are released over a longer period of time, i.e. up to two hours. Carbohydrates without fiber, like juice or soda are referred to as “fast acting” because the glucose is released into the blood stream more rapidly, i.e. 5-15 minutes.
  • The second way fiber helps with blood sugar control is by affecting how high the blood sugars rise after a meal. Foods with fiber typically don’t cause blood sugars to rise as high as foods without fiber. This blunting effect is important for controlling after meal (postprandial) blood sugars.

A final benefit of eating more fiber is that more stable blood sugars help maintain your energy level. The recommended fiber intake is about 25 to 30 grams a day. Fiber is found in whole fruit, vegetables, whole grains, and legumes (dried beans and peas). Foods that are high in fiber often have the added bonus of being nutrient rich. Some processed foods like cereal, bread, and snack bars may be fortified with fiber. Mindful eating encourages you to be curious so experiment with adding more fiber to your diet.

In the breakfast examples from the last post, How do carbs affect my blood sugar, you could try out a whole grain cereal, substitute whole fruit like blueberries for the juice, or choose a fiber containing lower-carb bagel. There may be other high fiber foods you’d like to try too, like whole grain crackers, stir-fried vegetables, hummus, beans and lentils, and salsa. Explore recipes here  and in Eat What You Love, Love What You Eat for Diabetes. Use mindful eating to increase your enjoyment of fiber rich foods. Notice the colors, textures, aromas, and flavors as you eat. The key is to keep an open mind and view this as an opportunity to discover healthful foods that you like.


About the author

Megrette Fletcher is a registered dietitian, certified diabetes educator, author, and co-founder of The Center for Mindful Eating. Megrette is the 2013-2014 president of The Center for Mindful Eating, a non-profit, organization to assist health professionals to explore the concepts of mindful eating. She has written articles for and has been quoted about mindful eating in Diabetes Self Management, Today’s Dietitian, Today’s Social Worker, Bariatric Times, Glamour, Family Circle, The Wall Street Journal, US News and World Report, Women’s Day, and Oxygen Magazine. Megrette currently works as a diabetes educator in Dover, New Hampshire.

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