What are complex carbohydrates?

Carbohydrates (or carbs) are one of the three macro-nutrients, the other two being protein and fat. Out of the three, they are often the most discussed, primarily because people fear that eating them will lead to weight gain.

Carbs can be broken down into three categories:

Sugars – these are short chain carbohydrates that are found in many foods. For example, fructose is the sugar that is found in fruits, whereas lactose is found in milk. Sugars give certain foods like fruit their sweet taste.

Starches – are made up of many glucose molecules that have been bonded together. When you eat starch, it is broken down and converted back into glucose by the digestive system. Starch rich foods include potatoes and beans.

Fiber – also known as roughage, fiber is found in plant based foods such as fruits and vegetables. It comes in two forms, soluble and insoluble, and cannot be digested by humans. Fiber consumption is beneficial for weight loss, cholesterol levels and gut health.

In scientific terms, sugars would be considered to be “simple” carbohydrates, and starches & fiber would be considered to be “complex”. Both simple and complex carbs are found in a wide range of foods.

A lot of people use the phrase “complex carbohydrates” to refer to foods that are considered healthy, and “simple carbohydrates” to those that are not. However, more suitable phrases would be “whole carbohydrates” and “refined carbohydrates”.

Whole carbs (i.e. complex carbs in this case) have undergone little or no processing, meaning they are also as close to their natural state as possible. Because of this, whole carbs retain significant amounts of vitamins, minerals and fiber.

Refined carbs on the other have undergone a lot of processing. Much of the fiber and many of the nutrients have been stripped away, leaving behind foods that provide almost no nutritional value; they are a source of empty calories. Examples of these foods include things like candy, soda and cake.

When foods high in refined carbs are eaten, they cause major spikes in blood sugar levels, resulting in the all too common “crashing” feeling people experience shortly after eating them. The large quantities of added sugar these foods contain is one of the reasons why they are linked to so many diseases.

Conversely, most whole carbs are digested slowly by the body, providing a steady release of energy. There have been plenty of studies showing that the consumption of whole carbs improves metabolic health and reduces the risk of disease.

Below are the foods that are sources of whole (or “complex”) carbs, and are the ones that are beneficial for overall health.

1. Unrefined grains

Grains such as oats, quinoa and brown rice are all made up of more than 60% carbohydrate. For example, 100 g of steel cut oats has 66 g of carbs, 11 g of which is fiber. It also provides you with many nutrients, including iron, magnesium, manganese, phosphorus and zinc.

Unrefined grains are very filling and leave you feeling satisfied for long periods of time. This is because the fiber in them absorbs water to form a thick gel that slows down the movement of food through the digestive system. Oats and quinoa also contain quite a bit of protein, which adds to their fullness factor.

Unrefined or “whole” grains contain all three original edible parts of the grain, which are the bran, endosperm and germ. Refined grains have the bran and germ removed during the processing process; this makes them much less nutritious. For this reason, it is better to opt for brown bread, rice and pasta over the white varieties.

2. Beans and legumes

Lentils, kidney beans and chickpeas are all carbohydrate and fiber rich foods. A cup of cooked lentils (198 g) has 40 g of carbohydrate, 15 g of which is fiber. Like unrefined grains, beans and legumes are both very filling, due to their high fiber and protein content.

These foods come in very handy when trying to lose weight. Not only do they help to satisfy your appetite, they are also low in calories; a cup of cooked lentils has only 230 calories. As an added benefit, beans and legumes are very affordable.

One thing to keep in mind is that it is important to prepare beans thoroughly before eating them, so as to avoid food poisoning. As a general rule of thumb, it is recommended that you soak them overnight and cook them in boiling water for at least 10 minutes before consuming them.

3. Fruit (not fruit juice)

Fruits contains large quantities of simple sugars, which is why they are so sweet. Dates, raisins, figs, grapes, mangoes and pineapples are all examples of sugar rich fruits. Certain fruits such as bananas increase in sugar content the riper they become.

Despite containing a lot of sugar, fruits are still considered to be whole carbs because they are rich in both fiber and nutrients. Many fruits contain vitamin C, which is needed by the body for numerous processes.

To keep sugar consumption in control, it is recommended that the average person should aim for 2 servings of fruit per day. If you lead an active lifestyle, you can have a little more.

4. Vegetables

The importance of vegetables is very well known, with experts recommending they should be abundant in your diet. The carb content of vegetables does vary quite a bit. Starchy vegetables such as potatoes and carrots are the most carb rich, whereas leafy vegetables such as spinach do still have carbs, but in smaller quantities.

Because veggies are mainly made up of water, they are low in calories (a cup of spinach only has 7 calories!). This, combined with their high fiber content means you can eat them in large quantities.

If you are trying to lose weight, vegetables should be at the top of your list of food choices. Because of their versatility, this should not be hard to achieve.

5. Nuts and seeds

These foods are the most calorie dense because they are mainly made up of fat, which has 9 calories per gram. They do still have significant amounts of carbohydrate. As an example, 100 g of almonds has 22 g of carbohydrate, 12 g of which is in the form of fiber.

Like with the other foods mentioned above, nuts and seeds are very nutritious, being a source of lots of vitamins, minerals and antioxidants. Because of this, they bring with them numerous health benefits.


Carbohydrate requirements will vary from person to person, depending on age, metabolism and overall goals. If you are trying to lose weight, the first thing you should do is replace refined carbs for whole (complex) ones.

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