Whether it's "low-carb," "no carb," "good carb," or "bad carb," the press has been buzzing with the topic of carbs, (or carbohydrates). While eating too many refined carbohydrate foods such as pastries, sweets, white rice or white bread can contribute to weight gain and make weight loss difficult, unrefined carbohydrate foods tend to have a very different effect.
What's Important About Carbs?
Carbohydrate is an essential fuel for muscle and other cells throughout the body and is necessary for proper function of body organs. In fact, carbohydrate is the preferred energy source for the brain, which needs about 130 grams of carbohydrate per day to function at its best. Carbohydrate foods are also important sources of vitamins, minerals and fiber. Your body depends on all of these for health!
When carbohydrates are digested, they are converted to a sugar called glucose. Glucose is absorbed through the intestinal wall and enters the bloodstream where it is transported to body cells to be used for energy. Glucose that is not immediately needed is stored in muscles and the liver as glycogen, a "storage form" of glucose. Glycogen can be broken down to glucose and used by the body when it needs energy, for example during exercise or during an extended fast. If excess calories are consumed from eating "too many" carbohydrate foods (something that is easy to do with refined carbs), the excess is stored as fat. This can contribute to unwanted pounds that you notice when you step on the scale.
Food Sources of Carbohydrate
Sources of carbohydrate include:
- fruits
- vegetables
- dairy foods
- grains
- legumes, dried beans and peas
- sweets including ice cream, cookies, cakes, and candy
Many variables influence the affect of carbohydrate-containing foods on blood glucose. In addition to the source of carbohydrate, other variables that influence blood glucose effect include:
Food-related variables:
- type of starch
- ripeness of fruits and vegetables
- food processing
- food preparation methods
- other nutrients (protein or fat) contained in a food
- nutrient mix of a complete meal that a food is part of
Other variables:
- blood glucose level before eating the food
- having insulin resistance
- level of circulating insulin (a consideration for people with diabetes)
Types of Carbohydrates
Carbohydrates in foods take different forms. Carbohydrates are typically categorized as either starches, fibers (non-digestible carbohydrates) or sugars. Though starches and fibers are generally beneficial, consuming too many refined starches or sugars can be detrimental to health. These are facts you should know about starches, fibers, and sugars.
Starches and Fibers
Starches are complex molecules that are digested slowly by the body. They are gradually broken down to glucose molecules. Fibers are also complex molecules. In fact, they are so complex that they cannot be broken down in the GI tract and pass through the body undigested. For this reason, fibers do not supply the body with either energy (calories) or nutrients. Fiber has been shown to blunt the rise in blood glucose level that occurs after a meal.
Dietary fiber is categorized in two types. Each type plays a unique role in supporting health.
Insoluble fiber does not dissolve in water and acts as a bulking agent. It helps maintain digestive health - especially by preventing constipation and reducing risk of diverticular disease. In addition, intake of high fiber (whole grain) cereals has been linked to lower risk of developing type 2 diabetes.
Sources include: whole wheat, bran, corn, whole-grain cereals, brown rice, bulgur, barley, vegetables and nuts and seeds.
Soluble fiber dissolves in water to form a gel-like substance. Soluble fiber has been shown to lower blood cholesterol levels and reduce risk of cardiovascular disease.
Sources include: oats, oat bran, psyllium, dried beans, peas and lentils, apples, citrus fruits, berries, and nuts and seeds.
Fiber Guidelines
Multiple health organizations including the American Dietetic Association (ADA), American Heart Association (AHA), American Diabetes Association (ADA) and the American Cancer Society (ACS) recommend eating at least twenty to thirty-five grams of fiber per day. To reach this goal, aim to consume 10 to 14 grams of fiber per 1000 calories. Always check the Nutrition Facts Label on food products to determine grams of fiber in foods. Choose those with three or more grams of fiber per serving. Take it slowly when increasing fiber intake by gradually adding high fiber foods. This will help prevent GI discomfort. And, drink plenty of fluids - at least eight- to-ten 8-oz glasses per day.
Whole Grain vs. Refined Grain
Whole grains are important sources of fiber and nutrients. A whole grain is an unprocessed plant kernel that contains three parts: the bran, germ, and endosperm. The bran is the fiber-rich part of a grain kernel. The germ is nutrient rich and is a good source of selenium, magnesium, potassium, B vitamins, and iron as well as other nutrients. The endosperm is the starchy, inner part of the grain.
Whole grains include: bread or pasta made from whole-wheat flour, rye, bulgur, oatmeal (but not the instant type), brown rice, buckwheat, popcorn, whole cornmeal, wild rice, and barley.
When grains are refined, the outer bran and some of the germ are removed leaving primarily just the starchy endosperm. Refining removes important dietary fiber, vitamins, minerals and other naturally-occurring plant nutrients. Though most refined grains are enriched with vitamins and iron after processing (meaning nutrients are added back), fiber is not added back. Because they lack fiber, refined grains are digested, converted to glucose, and absorbed into the blood stream quickly which leads to a rapid and significant increase in blood glucose and insulin levels. Due to this connection to elevated post-meal blood glucose and insulin levels, highly refined diets have been linked to obesity, development of type 2 diabetes and cardiovascular disease.
Refined grains include: white rice, white flour, bread and pasta products made from white flour, refined breakfast cereals , snack foods, grits, couscous, "instant" grain products (for example oatmeal or rice).
Sugars
Sugars include sucrose (table sugar), fructose (fruit sugar), lactose (milk sugar) and dextrose/glucose (corn sugar). Sugars were once called "simple carbohydrates," because they are simple molecules that are digested, converted to glucose, and used by body cells for energy very quickly. Many foods and beverages that are sources of sugar such as fruits, fruit juices, low fat milk or yogurt are healthy foods to include in a balanced eating plan. Others such as table sugar, candy, desserts, and sweetened drinks are best to enjoy occasionally and in moderate amounts. When sugar-containing foods are consumed in excessive amounts, calories add up! Diets that are high in sugars have also been linked to obesity, increased risk of type 2 diabetes and heart disease.
Additional sugar sources include: jellies and jams, honey, cookies, cakes, pastries, pies, ice cream, soft drinks.
The Bottom Line about Carbs
Minimally processed carbohydrate foods are healthy foods and are an important part of a well-balanced diet. In addition to providing all-important fiber, they are essential sources of vitamins and minerals including B vitamins, magnesium, potassium, iron and selenium and other plant-based nutrients. They also support GI, metabolic and heart health.
To get the most benefit from carbs, make wise choices by including plenty of fresh or frozen fruits and vegetables (including starchy vegetables such as peas, corn or potatoes), a variety of whole grains, beans, peas and lentils and low fat or fat-free dairy products. Save highly processed starches, cereals, and sweets for occasional enjoyment.
For more about healthy eating guidelines and the important role of carbohydrate foods in a well-balanced diet, visit: