Carbohydrate facts: Simple = bad, complex = good?
Studies have shown that low-carb diets are effective for weight loss, but that doesn't mean that eating carbs makes you fat.
In fact, there are plenty of health benefits associated with eating carb-containing foods, but that's only if you eat the right kinds.
While some high-carb foods are highly nutritious and even helpful for weight management, others are detrimental to your health.
What are carbs?
Wholemeal bread is a healthful source of complex carbs.
Carbohydrates, or carbs, are one of three macronutrients that provide the body with energy. The other two are protein and fat.
There are three major classes of carbs:
- Sugars: Individual sugar molecules or short chains of sugar molecules. These include glucose, fructose, galactose and sucrose
- Starches: Longer chains of carbohydrate molecules that need to be broken down in the digestive system.
- Fiber: Carbohydrates that the body cannot digest
The primary function of carbs is to provide the body with energy.
Most carbs are broken down into glucose in the digestive system and provide the body with fuel to perform essential functions.
Each gram of carbs provides the body with four calories. The exception to this is fiber, which generally does not provide many calories.
Bottom line: Carbohydrates are a macronutrient that provides the body with energy. Carbs include sugars, starches and fiber.
Not all carbs are created equal
Part of the reason there is so much confusion regarding carbs is that not all carbs are created equal.
Added sugars can harm your health.
People tend to classify all carbs as either good or bad, but that doesn't make sense.
There are major differences in the health effects of different types of carbs, so they cannot all be lumped into one group.
One way that carbs are classified is by the terms "simple" and "complex." Some people define all starch and fiber as complex carbs and all sugars as simple carbs.
However, this definition can be confusing. Some starchy foods like sweet potatoes, quinoa and legumes provide many health benefits, while other starch sources like refined wheat flour are associated with a myriad of health problems.
However, the natural sugars found in whole fruits and vegetables do not have the same negative effects.
It makes more sense to define complex and simple carbs this way:
- Complex carbs: Carbs found in whole, unprocessed foods, including fruits, vegetables, legumes and whole grains
- Simple carbs: Sugars and starches that have been refined and stripped of their natural fiber and nutrients
Bottom line: Complex carbs are found in whole, unprocessed foods. Simple carbs are found in processed foods and have little nutritional value
Complex carbs are highly nutritious, but simple carbs are not
Brown rice vs white rice
Complex carbs are healthier than simple carbs because they are generally nutrient dense. This means they contain a large amount of nutrients in relation to the number of calories they provide.
On the contrary, simple carbs contain "empty" calories, meaning they have calories, but very little nutritional value.
To highlight the nutritional differences between complex and simple carbs, let's compare whole grains and refined grains.
A whole grain contains three distinct parts:
- Germ: Part of the seed that's high in polyunsaturated fats and various important nutrients
- Endosperm: The inner portion of the grain that's mostly made up of starch
- Bran: The hard outer portion of the grain that's high in fiber and essential fatty acids
The germ and bran of a grain are where the majority of its nutrition is found.
Interestingly, when grains are processed and refined, the highly nutritious germ and bran are removed, leaving only the starchy endosperm.
|Whole flour||Refined flour|
|Carbs||87 grams||95.4 grams|
|Protein||16.4 grams||12.9 grams|
|Fat||2.2 grams||1.2 grams|
|Fiber||14.6 grams||3.4 grams|
|Thiamin (% RDI)||36%||10%|
|Riboflavin (% RDI)||15%||0%|
|Niacin (% RDI)||38%||8%|
|Vitamin B6 (% RDI)||20%||8%|
|Folate (% RDI)||13%||8%|
|Pantothenic acid (% RDI)||12%||5%|
|Iron (% RDI)||26%||8%|
|Magnesium (% RDI)||41%||7%|
|Phosphorus (% RDI)||42%||13%|
|Potassium (% RDI)||14%||4%|
|Zinc (% RDI)||23%||6%|
|Manganese (% RDI)||228%||43%|
|Selenium (% RDI)||121%||61%|
|Choline||37.4 mg||13 mg|
Whole wheat flour is a source of several important nutrients, but those nutrients are lacking in wheat flour that has been processed and refined.
The same is true for fruits and vegetables. In their whole forms, they contain small amounts of sugar, but they are also packed with vitamins, minerals and fiber.
Bottom line: Complex carbs, such as whole grains, fruits, vegetables and legumes, are highly nutritious. Simple carbs provide calories, but little nutritional value.
Health benefits of complex carbs
Carbs are not essential for life, but eating the right kind may benefit your health.
Complex carbs are less likely to cause blood sugar spikes
Simple carbs are digested very quickly, which causes a spike in your blood sugar.
Because complex carbs are digested more slowly, they provide sustained energy and help you feel full for longer (11).
Complex carbs may reduce your risk of some chronic diseases
Complex carbs promote a healthier digestive system
There are billions of "good" bacteria lining your intestines. They're known as your gut microbiota.
Soluble fibers found in complex carbs feed the beneficial bacteria and increase their presence in your gut. They also help the bacteria produce nutrients, such as short-chain fatty acids, which are beneficial for digestive health (23).
Complex carbs may reduce inflammation
While sugary foods and refined flours promote inflammation, complex carbs help reduce inflammation (26).
Strong>Bottom Line: Complex carbs like whole grains, legumes, fruits and vegetables have multiple health benefits.
Simple carbs can be detrimental to your health
Excessive consumption of simple carbs like refined grains and added sugars harms your body.
Below are some of the detrimental health effects of simple carbs:
- They contribute to overeating: Simple carbs break down quickly and cause a blood sugar roller coaster. Studies have found that these blood sugar spikes and crashes contribute to cravings, hunger and overeating (7, 8, 29).
- High triglyceride levels: Large amounts of refined carbs can lead to elevated triglyceride levels, which increase the risk of heart disease and type 2 diabetes (3, 30, 31, 32).
- Increased heart disease risk: Sugar and refined grains increase heart disease risk. A study found those who ate the most refined grains were 2 to 3 times more likely to develop heart disease than those who ate the least (33, 34, 35, 36, 37).
- Increased risk of type 2 diabetes: Excessive consumption of simple carbs can cause your cells to become resistant to insulin, which greatly increases your risk of type 2 diabetes (34, 38, 39, 40, 41).
- Sugar is addictive for some people: Similarly to recreational drugs, sugar causes the brain to release dopamine. For people that are prone to addiction, sugar can be highly addictive (42, 43).
- Increased chance of becoming obese: Simple carbs affect the levels of appetite hormones, making them likely to contribute to obesity (29, 44).
Bottom line: A diet high in refined carbs can have multiple negative health consequences.
Foods to eat and foods to avoid
Carbs can be a healthy part of your diet if you choose the right ones.
The healthiest carbs are from foods that are in their whole, unprocessed form.
Complex carbs to eat
Lentils and other pulses are a healthful form of carbohydrate.
The following foods are good carbs to include in your diet:
- Whole grains: Whole, unprocessed grains like oats, quinoa, barley and brown rice.
- Legumes: Lentils, black beans, kidney beans, black-eyed peas, etc.
- Vegetables: Sweet potatoes, broccoli, green beans, carrots, asparagus, etc.
- Fruits: Apples, berries, oranges, kiwi, etc.
- Nuts and seeds: Almonds, walnuts, peanuts, chia seeds, etc.
Refined carbs to limit or avoid
These foods tend to contain mostly refined carbs and should be limited:
- Sugary beverages: Soft drinks, sweetened tea, sports drinks, fruit juices, etc.
- Desserts and sweets: Donuts, cakes, cookies, ice cream, candy, etc.
- White bread: This includes "white wheat" bread.
- White pastas: These are made from refined wheat flour.
Bottom line: Complex carbs that are in their whole form are generally healthy foods that are rich in fiber and nutrients.
Complex carbs are far more nutritious than simple carbs.
They are high in nutrients and fiber, and eating them on a regular basis can be beneficial for your health and waistline.
On the other hand, simple carbs provide little to no nutritional value and should be avoided as much as possible.