The Importance of Carbohydrates – What Do they Do & What Foods are Carbs?

Importance of Carbohydrates - what foods are carbs & what do they do

Carbohydrates have been given a bad name due to popular low-carb diets over the years. But are all carbs bad? Here we will discuss what they do and the importance of eating carbohydrate-containing foods


What are Carbohydrates?

Carbohydrates are all the sugars from foods that our body converts to sugar (blood glucose) which is used, or stored for energy. Carbohydrates contains carbon, hydrogen and oxygen, which together form sugar molecules


The Importance of Carbohydrates – Why we need Carbs 

It is really important to get enough carbohydrates in your diet because it our body’s preferred source energy & is the best fuel for working muscles. Our brain, muscles & nervous system all rely on glucose as their main source of fuel. Carbs also provides fiber and many essential vitamins, minerals & antioxidants in our diet


What Do Carbohydrates Do? 

Carbohydrates are used for:

  • energy during exercise
  • energy for the brain

Glucose is stored for:

  • energy in the muscles
  • maintains stable blood glucose levels

Excess glucose is:

  • stored as fat


Distribution of glucose after a meal

Glucose from a 90 gram meal gets used for:

25 grams stored as glycogen in muscles

23 grams to muscle (used for energy)

17 grams stored as glycogen in liver

15 grams used for brain

8 grams used for kidneys

2 grams stored in fat deposits


How are Carbohydrates Digested, Stored & Metabolized?

Digestion of carbohydrates starts in the mouth where the enzyme a-amylase from the salivary glands hydrolyses (add water) to break down some of the sugars. The small intestines break down the rest of the sugars in to simple sugars

Once these sugars are broken down, they are carried to each cell through the bloodstream. The pancreas secretes insulin which helps to transport glucose in to the cells. Once inside the cell, glucose is ‘burned’ to produce energy. Excess glucose is converted to glycogen (storage form of glucose) in the muscles & liver. The energy stored (glycogen) gets released when sugar levels drop too low between meals or during physical activity

Fructose and galactose is metabolized slightly differently – these are metabolized by the liver


What Foods Are Carbs?

Carbs are not just found in breads, rice & pastas, they are in many other foods, including:

  • Breads & Cereals
  • Rice & Pastas
  • Fruits & Vegetables
  • Beans & Legumes
  • Nuts & Seeds
  • Milk, Yogurt & Cheese
  • Soda & Juices
  • Sweets, Candy & Desserts
  • and in many other Processed Foods


How Much Carbs Do we Need?

It is recommended that 45-65% of your total calories come from carbohydrates sources (230-310 grams per day). Consume at least 3 servings of wholegrains a day and make approximately 1/4 of your plate whole grain foods. See the Basic Healthy Guidelines for more on serving sizes for whole grain foods


What are Healthy Carbohydrates?

Importance of Carbohydrates - What do they do & What foods are good carbs

Healthy carbs are those found in most whole foods, including:

  • Fruit (& small amounts in non-starchy vegetables)
  • Starchy Vegetables (eg. sweet potato, potatoes, taro)
  • Beans & Legumes (small amounts)
  • 100% Wholegrain breads, cereals & crackers
  • Brown rice & pastas
  • Other whole grains such as oats, quinoa, buckwheat etc

These carbohydrates are healthy because of the following reasons:

  • High in fiber, vitamins, minerals & protective antioxidants
  • Contain natural sugars
  • Results in prolonged, long lasting energy
  • Feel full on fewer calories
  • Promotes weight loss

When choosing bread, cereals, rice & pastas – go for high fiber varieties. Use the 10:1 ratio as a guide – for every 10 grams carbs, grains should have at least 1 gram of fiber (or at least 5 grams per 100 grams)


What are Unhealthy Carbohydrates?

Importance of Carbohydrates - What do they do & What foods are bad carbs

Unhealthy carbs are commonly found in processed, refined foods, including:

  • Sodas & juices
  • Sweets, candy & desserts
  • White bread, rice & pasta
  • Sugary cereals
  • Cakes, biscuits, muffins
  • Bottled sauces
  • French fries, potato chips
  • White flour products

These carbohydrates are unhealthy because of the following reasons:

  • Low amounts or absence of fiber & nutrients
  • Usually contain added sugars
  • Gives you energy but is only short lasting (causes ‘sugar crash’)
  • Need lots of calories to make you feel full
  • Excess amounts are converted to fat
  • Large amounts consumed are associated with obesity & chronic disease outcomes

These foods often contain, high amounts of added sugar as well as added fat & salt as well. Avoid foods that contain refined sugars – or choose foods that contain less than 10 grams of sugar per 100 grams


Here is a Visual Representation of the Differences Between Healthy & Unhealthy Carbs

Importance of Carbohydrates - What do they do & What foods are carbs good vs bad


Types of Carbohydrates

There are 3 Types of Carbohydrate – sugar, starches and fiber

Importance of Carbohydrates - What do they do & What foods are carbs chart

Types of Sugars

Monosaccarides (one sugar molecule, simple sugars)

  • Glucose (or dextrose)
  • Fructose (found in fruit & honey)
  • Galactose

The following types of carbohydrates are made up of monosaccharides (simple sugars):

Disaccaharides (2 sugar molecules)

  • Sucrose (found in table sugar) made up of glucose + fructose
  • Lactose (found in milk sugar) made up of glucose + galactose
  • Maltose (found in malt sugar) made up of glucose + glucose

Oligosaccarides (2-10 sugar molecules)

  • Raffinose
  • Stachyose

Polysaccharides (10 or more sugar molecules)

  • Starch (how plants store glucose)
  • Cellulose (structural component of plant cell walls)
  • Glycogen (our bodies store glucose as glycogen)

Polysaccacarides must be hydrolysed (broken down) to monosaccharides (simple sugars)



Starch is made up of long chains of glucose – found most abundantly in seeds, grains, tubers, roots, fruits, corn, potato, rice, wheat and tapioca (cassava)

Foods with high starch content – rice, pasta, breads, corn, potatoes


3 Types of Starch:

1. Rapidly Digestible Starch eg. starch cooked in moist heat, bread, potatoes

2. Slowly Digestible Starch (nutritionally the most desirable starch) eg. pasta, parboiled rice, muesli, legumes

3. Resistant Starch – fermented by microflora bacteria in large intestine eg. found in grains, seeds & pasta, raw potato and banana starch. Resistant Starch is similar to dietary fiber


Starch Derivatives:
  • High fructose corn syrup
  • Maltodextrins
  • Corn syrups
  • Sugar alcohols


Dietary Fiber

Non-starch Polysaccharides (NSP’s) (Dietary Fibre):

  • soluble and insoluble
  • cannot be digested
  • absorbed in the small intestine
  • fermented by gut to produce short chain fatty acids (reabsorbed)
  • no nutritional value – no calories or energy


Here are two Infographics summarizing ‘Carbohydrates’

Importance of carbohydrates - what foods are carbs & what do they do

Importance of carbohydrates - what foods are carbs & what do they do - good vs bad

Learn more about the Glycemic Index Here


In Conclusion

The types of carbs you eat make a huge difference to how healthy your diet is

Choose nutrient rich carbohydrates from fruit, vegetables, legumes, whole grains, nuts & seeds. These carbs will keep you fuller for longer, curb your cravings, give you more energy & assist in weight loss because of the many nutrients & fiber that accompany most of these foods

Limit carbs from refined grains, processed foods, sweets, soda & juice. These foods lack fiber & many essential nutrients, leaving you feeling tired & hungry sooner, with little to no energy shortly after. It is also easy to over eat on these types of foods which can lead to excess calories being consumed and eventually weight gain

Eating a healthy, well balanced diet will prevent these rapid swings in blood sugar levels. Learning how to balance your intake of carbs can keep your body fueled as well as help you to lose or maintain your weight

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