All of the food you eat is made up of just three main nutrients: fat, carbohydrates, and protein. Carbohydrates in food and drinks break down into glucose in the body. When people without diabetes eat carbs, their blood sugar rises, and the insulin response kicks in to move the blood sugar to the cells for fuel.
But in people with type 2 diabetes, the insulin response doesn’t work properly, and your blood glucose levels remain elevated. The three types of carbohydrates are fiber, starch, and sugar—and these carbs are not created equal.
Dietary fiber is found in plant-based foods, including fruits, vegetables, beans, and whole grains. Fiber is plant cell material that the human digestive system can’t break down. It makes you feel full, helps lower your cholesterol and blood sugar, improves digestion, and reduces the risk of colon cancer. While sugar and starch increase your blood glucose levels, fiber doesn’t.
The two important types of dietary fiber are soluble and insoluble.
Water-soluble fiber absorbs water during digestion and turns into a gel, which slows down digestion. Soluble fiber helps lower cholesterol, stabilize blood sugar, and reduce the risk of heart disease.
Sources of soluble fiber include oat bran, barley, beans, lentils, nuts and seeds, and some fruits and vegetables.
Water-insoluble fiber doesn’t change as you digest it. Insoluble fiber promotes efficient movement of the contents of the intestine, adds bulk to the stool, and helps reduce the risk of colon cancer.
Sources of insoluble fiber include the peels and seeds of fruits and vegetables, whole-grain products, and wheat bran.
Recommended daily fiber intake
The American Heart Association recommends a daily intake of 25 to 30 grams of fiber each day from food. The U.S. Department of Veterans Affairs Nutrition and Food Services breaks down recommended fiber intake by age and sex:
- Men age 49 and under: 38 grams per day
- Men age 50 and over: 30 grams per day
- Women age 49 and under: 25 grams per day
- Women age 50 and over: 21 grams per day
Although there are no official guidelines for how much of the fiber you eat should be soluble and insoluble, many experts suggest that soluble fiber should account for around 25 percent of your daily fiber intake—or around six to eight grams per day of soluble fiber. However, if you consume a varied diet with lots of whole grains, beans, legumes, fruits, and vegetables, there’s no need to keep track of insoluble and soluble fiber—you’re likely getting plenty of both.
Fiber content in popular foods
Foods that are high in fiber are often labeled as such. If a food contains at least 2.5 grams of fiber per serving, it’ll be labeled as a “good source” of fiber. If it contains more than 5 grams per serving, it’ll be labeled as an “excellent source” of fiber. The following foods have three or more grams of fiber per serving:
- One whole apple (3), orange (4), pear (5),
- 1 cup strawberries (3), blueberries (4), raspberries (8), blackberries (8)
- 1/2 avocado (5)
- 1/2 cup of most types of beans (7)
- 1/2 cup lentils (8)
- 1 cup popcorn (1)
- 3 tablespoons flax seed (7)
- 1/4 cup sunflower seeds (3)
Should you try a high-fiber diet?
A recent study found that people with type 2 diabetes and hypertension (high blood pressure) who consumed a high-fiber diet for six months showed significant reductions in several risk factors for cardiovascular disease:
- Blood cholesterol level: nine percent reduction
- Triglycerides: 15 percent reduction
- Systolic blood pressure: 15 percent reduction
- Fasting glucose: 28 percent reduction
For the study, researchers increased the recommended dietary allowance (RDA) for dietary fiber by 20 to 25 percent, based on an RDA of 40 grams per 2,000 calories (24g/1,200 calorie diet or 30g/1,500 calorie diet) For those consuming 2,000 calories per day, a high-fiber RDA would be 48 to 50 grams (29 to 30g/1,200 calorie diet or 36 to 38g/1,500 calorie diet.)
Eating more than 45 grams of fiber per day can cause abdominal pain, constipation, and other digestive woes and may prevent the effective absorption of minerals like calcium and iron. A high-fiber diet without adequate water consumption can lead to a rare but potentially fatal intestinal obstruction. Before you dramatically increase your fiber intake above the RDA, talk to your doctor to see if a high-fiber diet is right for you.
Starch is a carbohydrate found in whole grains, pasta, white and brown rice, breads and crackers, beans, lentils, peas, and starchy vegetables like corn, squash, and potatoes.
Although starches in general cause blood sugar to rise, you shouldn’t consider all starches an enemy if you have type 2 diabetes. Healthy starches contain vitamins and minerals, dietary fiber, and natural sugar. Three different classes of starch in foods are rapidly digestible starch, slowly digestible starch, and resistant starch.
Resistant starch is a starch that isn’t digested by enzymes in the stomach and small intestines. Rather, it passes on to the large intestine, and it has many of the same effects as dietary fiber, including slower digestion, lower post-meal blood glucose, and making you feel fuller. Like dietary fiber, resistant starch is fermented in the gut, increasing the production of short-chain fatty acids. Research shows that resistant starch may help with digestive health, weight loss, blood sugar management, and even insulin sensitivity.
Foods that contain resistant starch include:
- Brown rice. Brown rice has a high fiber content and is a good source of resistant starch, especially when it’s cooled.
- Most types of beans and legumes. Pinto beans, black beans, soybeans, peas, and other beans and legumes are packed with fiber, and they have one to five grams of resistant starch per serving.
- Cooked and cooled potatoes. Eaten warm, the starch in potatoes is quickly digested. But when left to cool, and eaten cool or cold (not reheated!) potatoes are a great source of resistant starch.
- Green bananas. If you’re a fan of unripened bananas, green bananas are high in resistant starch, which makes up around 70 percent of their dry weight. But as they ripen, the starch is converted into sugars, and the banana only contains about one percent resistant starch.
Sugar is found naturally in some foods, and it’s added to others. Added sugars account for a large amount of the sugar Americans consume, and they’re linked to obesity, type 2 diabetes, inflammation, and heart disease.
- Naturally occurring sugars are found in foods like fruit and dairy products. Fruit sugar is known as fructose, and milk sugar is known as lactose.
- Added sugars are added to the food during processing and are found in large amounts in candy, baked goods, and regular soda. They’re found in smaller amounts in everything from pasta sauces and condiments to crackers, bread, and prepared packaged meals. Added sugars go by a variety of names on a food label, including dextrose, fructose, lactose, beet sugar, corn syrup, and honey.
Sugar alcohols are often found on the labels of foods labeled “no sugar added” or “sugar-free.” These sweeteners have around half the calories of regular sugar. Some sugar alcohols occur naturally, while others are man-made.
Sugar alcohols aren’t sugar, and they aren’t alcohol. But they are carbohydrates that can raise your blood sugar, although sugar alcohols are processed differently by the body than other carbohydrates. While some may raise your blood sugar a little, others may not affect your blood sugar at all.
Erythritol is a type of sugar alcohol that may not increase your blood sugar, and it’s popular in low-carb, “keto” foods. Even though sugar alcohols make sweets “sugar-free,” count the carbs, as always.
Sugar substitutes like saccharin, aspartame, sucralose, and stevia are, in general, nonnutritive, which means they contain very few or no calories and have very little or no impact on blood sugar. Sugar substitutes are far sweeter than sugar, so they’re used in smaller amounts. Most sugar substitute products don’t break down in the body, which means they pass through the body without providing calories.
While there’s no scientific evidence that shows using sugar substitutes helps control blood sugar or weight in the long run, the potential reduction in calories and carbs in foods with sugar substitutes may help some people better manage their blood sugar and weight.
What are some different ways to count carbs?
People who have type 1 diabetes—and those with type 2 diabetes who require insulin—need to carefully count their carbohydrate intake, because the amount of carbs they eat determines how much insulin they need.
But for those with type 2 diabetes that’s controlled with metformin or another glucose-control medication, carb counting doesn’t have to be as complicated. Here are some ways to count carbs for better food choices.
How many carbs should you eat?
The recommended intake of carbohydrates for people with type 2 diabetes is all over the map. For example, the Centers for Disease Control notes that people with diabetes should get around half of their calories from carbs. Since one gram of carbohydrate contains four calories, someone eating 2,000 calories per day would consume around 200 grams of carbohydrates.
But a 2019 literature review of articles related to the reversal of type 2 diabetes found that 94 percent of people who consume a low-carb diet of under 130 grams per day were able to discontinue their diabetes medication—and after one year, 84 percent were still in remission. Additionally, 95 percent of those who consumed a very-low-carb diet of 20 to 30 carbs per day — essentially a keto diet — were able to reduce or discontinue taking diabetes medication after just 24 weeks.
Use the glycemic index: Simple carbs vs. complex carbs
Not all carbohydrates are created equal. Some carbohydrates raise your blood sugar more than others. The glycemic index (GI) is a helpful tool that scores foods on a scale of 1 to 100. Foods that score lower don’t raise your blood sugar as quickly as those with higher scores. A 2019 review found that in general, a low-GI diet reduces hemoglobin A1C in people with type 2 diabetes and prediabetes.
The glycemic index is a helpful tool to help you become familiar with the types of foods that raise your blood sugar slowly. But it does have some limitations—just because a food is low on the GI doesn’t mean it’s a healthy food, and just because it’s high on the index doesn’t mean it’s unhealthy.
Foods are ranked on the glycemic index from 1 to 100. :
- Low: 55 or lower
- Medium: 56 to 69
- High: 70 or higher
- More refined foods will have a higher GI.
- The longer a food is cooked, the faster its sugars are digested, and the higher the GI.
- Foods with resistant starch will have a lower GI than those with more digestible starches.
- Riper fruit has a higher GI than less-ripe fruit—for example, an unripe banana has a GI of 30, while a very ripe banana earns a 48 (which is still considered low.)
- You can lower the impact of a higher-GI food on your blood sugar by adding fat and protein
Count carbohydrate “choices” or “servings”
Some people with type 2 diabetes count their carbs as “choices” or “servings.” One carbohydrate choice or serving equals 15 grams of carbs. Carbohydrate servings aren’t the same thing as a serving size. For example, a small potato counts as one food serving, but it counts as two carb servings, because it has 30 grams of carbs.
Use the plate method
To use the plate method of counting carbs, fill half of a 9-inch plate with non-starchy vegetables, fill one-quarter with a serving of lean protein, and fill the remaining one-quarter with a serving of low-carb, whole grains, starchy vegetables, beans, legumes, fruit, milk, or yogurt.
Forward can help you take control of your type 2 diabetes
Forward’s Heart Health Program helps you manage all of your risks for heart disease, including type 2 diabetes. This 12-week, doctor-led program includes a range of assessments and blood tests as well as a personalized plan for managing your heart disease risks with ongoing monitoring. As your primary care provider, Forward has a range of resources, including our Weight Management Program, to help you get your type 2 diabetes under control—and possibly even reverse it.