Updated 10 October 2013

Why your body needs sugar

Our bodies all need sugar (or glucose) to function, which in my mind is why we all should eat sugar, or at least foods that convert into sugar, writes registered dietitian Kim Hoffmann.

Our bodies all need sugar (or glucose) to function, which in my mind is why we all should eat sugar, or at least foods that convert into sugar. But before you get up in arms over this statement, let’s take a look at what sugar is, what form we need to take it in and how we should give it to our body for best physiological functioning.

What is sugar?

Sugar is a simple carbohydrate that comes in many different forms. In its simplest form it is called a monosaccharide and includes:

  • Glucose (occurs naturally in fruits and plant juices)
  • Fructose (occurs naturally in fruits, some root vegetables, cane sugar and honey)
  • Galactose (combines with glucose to form lactose) 

The "table sugar" sucrose is a disaccharide (contains two monosaccharaides) made up of glucose and fructose. All carbohydrates, once eaten, are converted into glucose during digestion, which is the form of sugar that is used in our bodies. 

It is the added sugar that gives no beneficial nutrients (just energy) and in excess can impact on our health. The World Health Organization guideline is that "added sugar" should make up no more than 10% of our daily intake. However, with sugar being used in many of our foods these days it is easy to lose track of how much "added" sugar you are eating in a day!  

The important message that I want you to remember is that glucose is necessary for our health and all of the cells in our body need it to function, but too much will increase the risk of several diseases, so we need to find the balance.

Understanding the difference between natural sugar and added sugar

Food labels only contain information on total sugars per serving ("of which sugars"), not added sugar. It therefore becomes almost impossible for us to work out how much added sugars are in the foods and drinks.

This is where the ingredient list becomes important. The ingredients in a product are listed in order of weight. This means that the biggest (by weight) ingredient comes first on the list and the smallest ingredient is last. Therefore if sugar is listed in the top five ingredients then the "of which sugars" is added sugar. If however the "of which sugars" is high and the first ingredient is milk or fruit, then it is natural sugar in the product.

Sugar Synonyms:

Beet sugar                                             Fructose                                                 Mannitol
Brown sugar                                           Galactose                                               Maple sugar
Cane sugar                                             Glucose                                                  Molasses
Corn sugar                                             Honey                                                    Sorbitol
Corn syrup                                             Invert sugar                                            Sucrose
Dextrin                                                  Lactose                                                 White sugar
Dextrose                                                Maltose

Which carbohydrate and how much?

It is the "which" carbohydrate and "how much" carbohydrate that is the most important part of any eating plan. It does not matter whether you choose to eat bread or fruit or yoghurt. It matters however that you choose the seed loaf over the white bread, and it matters that you eat 1-2 slices of bread rather than 4-6.

(Carbohydrates include fruit, starches, starchy veg, yoghurt and milk. A unit of carbohydrate is a slice of bread, ½ cup starch, a tennis ball size of fruit or 175ml yoghurt.)

As I have mentioned, all carbohydrates convert into sugar. It is the rate at which they are digested and converted into sugar that is important.

You have probably heard about the Glycaemic Index. This is a measure of how quickly or slowly the carbohydrates are digested and what impact they have on the blood sugar level. The lower GI, higher fiber carbohydrates are the ones that digest more slowly and therefore release their sugar into the blood more slowly resulting in more constant blood sugar levels. These are the carbohydrates you should choose most of the time. 

As an example, let’s take a look at bread. There are many different types of bread, and although all of them are carbohydrates and will convert into sugar, the rate of conversion between white bread and seed loaf is very evident. Eating seed loaf will keep you fuller for longer and thereby control the intake of your next meal.

Portion control

Blood sugar control is also dependent on how much carbohydrate you eat at each meal and snack. Logically it makes sense that if you eat a lot of food that converts into sugar, a lot of sugar will move into the blood – even if it is a low GI carbohydrate! 

Portion control therefore becomes a very important part of the equation. Generally about 1-4 units of carbohydrate can be eaten at each meal and snack. The number that you can eat depends on whether you are male or female, whether you are having snacks in between the meals and how active you are. 

For example, a female doing limited exercise can eat between 1 and 2 units of carbohydrates at each meal and snack and should aim at having about 9-11 units of carbohydrates per day. Within the carbohydrates you should of course be choosing about 2-4 servings of fruit and 1-2 servings of milk/yoghurt. To learn more about how to balance your carbohydrates (as well as proteins and fats) visit a dietitian who can help you with this.

The bottom line is that you need glucose. Carbohydrates are the foods that give you immediate glucose and you ideally need these regularly within the day to keep your blood sugar levels constant. And this means adding small amounts of lower GI, higher fiber carbohydrates to each meal. Enjoy!

Written by registered dietician, Kim Hoffmann, of The Lean Aubergine Dietetic Services. To sign up for the monthly Lean Aubergine newsletter send an e-mail to or


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